Merge branch 'rebase-i'

This works around the problem described in
https://github.com/git-for-windows/git/issues/542

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

git-rebase--interactive.sh

@@ -610,7 +610,7 @@ do_next () {
 		read -r command rest < "$todo"
 		mark_action_done
 		printf 'Executing: %s\n' "$rest"
-		${SHELL:-@SHELL_PATH@} -c "$rest" # Actual execution
+		"${SHELL:-@SHELL_PATH@}" -c "$rest" # Actual execution
 		status=$?
 		# Run in subshell because require_clean_work_tree can die.
 		dirty=f

t/t3404-rebase-interactive.sh

@@ -62,7 +62,7 @@ test_expect_success 'setup' '
 
 # "exec" commands are ran with the user shell by default, but this may
 # be non-POSIX. For example, if SHELL=zsh then ">file" doesn't work
-# to create a file. Unseting SHELL avoids such non-portable behavior
+# to create a file. Unsetting SHELL avoids such non-portable behavior
 # in tests. It must be exported for it to take effect where needed.
 SHELL=
 export SHELL