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56d388e6ad
When computing a diff in a partial clone, there is a chance that we could trigger a prefetch of missing objects at the same time as we are freeing entries from the global diff queue. This is difficult to reproduce, as we need to have some objects be freed from the queue before triggering the prefetch of missing objects. There is a new test in t4067 that does trigger the segmentation fault that results in this case. The fix is to set the queue pointer to NULL after it is freed, and then to be careful about NULL values in the prefetch. The more elaborate explanation is that within diffcore_std(), we may skip the initial prefetch due to the output format (--name-only in the test) and go straight to diffcore_skip_stat_unmatch(). In that method, the index entries that have been invalidated by path changes show up as entries but may be deleted because they are not actually content diffs and only newer timestamps than expected. As those entries are deleted, later entries are checked with diff_filespec_check_stat_unmatch(), which uses diff_queued_diff_prefetch() as the missing_object_cb in its diff options. That can trigger downloading missing objects if the appropriate scenario occurs to trigger a call to diff_popoulate_filespec(). It's finally within that callback to diff_queued_diff_prefetch() that the segfault occurs. The test was hard to find because it required some real differences, some not-different files that had a newer modified time, and the order of those files alphabetically was important to trigger the deletion before the prefetch was triggered. I briefly considered a "lock" member for the diff queue, but it was a much larger diff and introduced many more possible error scenarios. Signed-off-by: Derrick Stolee <stolee@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
219 lines
6.8 KiB
Bash
Executable File
219 lines
6.8 KiB
Bash
Executable File
#!/bin/sh
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test_description='behavior of diff when reading objects in a partial clone'
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. ./test-lib.sh
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test_expect_success 'git show batches blobs' '
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test_when_finished "rm -rf server client trace" &&
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test_create_repo server &&
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echo a >server/a &&
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echo b >server/b &&
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git -C server add a b &&
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git -C server commit -m x &&
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test_config -C server uploadpack.allowfilter 1 &&
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test_config -C server uploadpack.allowanysha1inwant 1 &&
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git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
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# Ensure that there is exactly 1 negotiation by checking that there is
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# only 1 "done" line sent. ("done" marks the end of negotiation.)
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GIT_TRACE_PACKET="$(pwd)/trace" git -C client show HEAD &&
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grep "fetch> done" trace >done_lines &&
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test_line_count = 1 done_lines
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'
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test_expect_success 'diff batches blobs' '
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test_when_finished "rm -rf server client trace" &&
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test_create_repo server &&
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echo a >server/a &&
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echo b >server/b &&
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git -C server add a b &&
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git -C server commit -m x &&
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echo c >server/c &&
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echo d >server/d &&
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git -C server add c d &&
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git -C server commit -m x &&
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test_config -C server uploadpack.allowfilter 1 &&
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test_config -C server uploadpack.allowanysha1inwant 1 &&
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git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
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# Ensure that there is exactly 1 negotiation by checking that there is
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# only 1 "done" line sent. ("done" marks the end of negotiation.)
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GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff HEAD^ HEAD &&
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grep "fetch> done" trace >done_lines &&
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test_line_count = 1 done_lines
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'
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test_expect_success 'diff skips same-OID blobs' '
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test_when_finished "rm -rf server client trace" &&
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test_create_repo server &&
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echo a >server/a &&
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echo b >server/b &&
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git -C server add a b &&
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git -C server commit -m x &&
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echo another-a >server/a &&
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git -C server add a &&
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git -C server commit -m x &&
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test_config -C server uploadpack.allowfilter 1 &&
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test_config -C server uploadpack.allowanysha1inwant 1 &&
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git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
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echo a | git hash-object --stdin >hash-old-a &&
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echo another-a | git hash-object --stdin >hash-new-a &&
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echo b | git hash-object --stdin >hash-b &&
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# Ensure that only a and another-a are fetched.
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GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff HEAD^ HEAD &&
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grep "want $(cat hash-old-a)" trace &&
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grep "want $(cat hash-new-a)" trace &&
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! grep "want $(cat hash-b)" trace
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'
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test_expect_success 'when fetching missing objects, diff skips GITLINKs' '
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test_when_finished "rm -rf sub server client trace" &&
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test_config_global protocol.file.allow always &&
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test_create_repo sub &&
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test_commit -C sub first &&
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test_create_repo server &&
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echo a >server/a &&
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git -C server add a &&
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git -C server submodule add "file://$(pwd)/sub" &&
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git -C server commit -m x &&
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test_commit -C server/sub second &&
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echo another-a >server/a &&
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git -C server add a sub &&
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git -C server commit -m x &&
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test_config -C server uploadpack.allowfilter 1 &&
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test_config -C server uploadpack.allowanysha1inwant 1 &&
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git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
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echo a | git hash-object --stdin >hash-old-a &&
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echo another-a | git hash-object --stdin >hash-new-a &&
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# Ensure that a and another-a are fetched, and check (by successful
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# execution of the diff) that no invalid OIDs are sent.
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GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff HEAD^ HEAD &&
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grep "want $(cat hash-old-a)" trace &&
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grep "want $(cat hash-new-a)" trace
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'
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test_expect_success 'diff with rename detection batches blobs' '
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test_when_finished "rm -rf server client trace" &&
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test_create_repo server &&
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echo a >server/a &&
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printf "b\nb\nb\nb\nb\n" >server/b &&
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git -C server add a b &&
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git -C server commit -m x &&
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rm server/b &&
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printf "b\nb\nb\nb\nbX\n" >server/c &&
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git -C server add c &&
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git -C server commit -a -m x &&
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test_config -C server uploadpack.allowfilter 1 &&
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test_config -C server uploadpack.allowanysha1inwant 1 &&
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git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
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# Ensure that there is exactly 1 negotiation by checking that there is
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# only 1 "done" line sent. ("done" marks the end of negotiation.)
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GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff --raw -M HEAD^ HEAD >out &&
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grep ":100644 100644.*R[0-9][0-9][0-9].*b.*c" out &&
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grep "fetch> done" trace >done_lines &&
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test_line_count = 1 done_lines
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'
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test_expect_success 'diff succeeds even if entries are removed from queue' '
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test_when_finished "rm -rf server client trace" &&
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test_create_repo server &&
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for l in a c e g i p
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do
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echo $l >server/$l &&
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git -C server add $l || return 1
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done &&
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git -C server commit -m x &&
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for l in a e i
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do
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git -C server rm $l || return 1
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done &&
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for l in b d f i
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do
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echo $l$l >server/$l &&
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git -C server add $l || return 1
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done &&
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git -C server commit -a -m x &&
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test_config -C server uploadpack.allowfilter 1 &&
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test_config -C server uploadpack.allowanysha1inwant 1 &&
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git clone --filter=blob:limit=0 "file://$(pwd)/server" client &&
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for file in $(ls client)
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do
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cat client/$file >$file &&
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mv $file client/$file || return 1
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done &&
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git -C client diff --name-only --relative HEAD^
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'
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test_expect_success 'diff does not fetch anything if inexact rename detection is not needed' '
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test_when_finished "rm -rf server client trace" &&
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test_create_repo server &&
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echo a >server/a &&
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printf "b\nb\nb\nb\nb\n" >server/b &&
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git -C server add a b &&
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git -C server commit -m x &&
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mv server/b server/c &&
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git -C server add c &&
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git -C server commit -a -m x &&
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test_config -C server uploadpack.allowfilter 1 &&
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test_config -C server uploadpack.allowanysha1inwant 1 &&
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git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
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# Ensure no fetches.
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GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff --raw -M HEAD^ HEAD &&
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test_path_is_missing trace
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'
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test_expect_success 'diff --break-rewrites fetches only if necessary, and batches blobs if it does' '
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test_when_finished "rm -rf server client trace" &&
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test_create_repo server &&
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echo a >server/a &&
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printf "b\nb\nb\nb\nb\n" >server/b &&
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git -C server add a b &&
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git -C server commit -m x &&
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printf "c\nc\nc\nc\nc\n" >server/b &&
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git -C server commit -a -m x &&
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test_config -C server uploadpack.allowfilter 1 &&
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test_config -C server uploadpack.allowanysha1inwant 1 &&
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git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
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# Ensure no fetches.
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GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff --raw -M HEAD^ HEAD &&
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test_path_is_missing trace &&
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# But with --break-rewrites, ensure that there is exactly 1 negotiation
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# by checking that there is only 1 "done" line sent. ("done" marks the
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# end of negotiation.)
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GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff --break-rewrites --raw -M HEAD^ HEAD &&
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grep "fetch> done" trace >done_lines &&
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test_line_count = 1 done_lines
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'
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test_done
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