gc/repack: release packs when needed

On Windows, files cannot be removed nor renamed if there are still
handles held by a process. To remedy that, we introduced the
close_all_packs() function.

Earlier, we made sure that the packs are released just before `git gc`
is spawned, in case that gc wants to remove no-longer needed packs.

But this developer forgot that gc itself also needs to let go of packs,
e.g. when consolidating all packs via the --aggressive option.

Likewise, `git repack -d` wants to delete obsolete packs and therefore
needs to close all pack handles, too.

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

builtin/gc.c

@@ -473,8 +473,10 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 
 	report_garbage = report_pack_garbage;
 	reprepare_packed_git();
-	if (pack_garbage.nr > 0)
+	if (pack_garbage.nr > 0) {
+		close_all_packs();
 		clean_pack_garbage();
+	}
 
 	if (auto_gc && too_many_loose_objects())
 		warning(_("There are too many unreachable loose objects; "

builtin/repack.c

@@ -304,6 +304,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	if (!names.nr && !quiet)
 		printf("Nothing new to pack.\n");
 
+	close_all_packs();
+
 	/*
 	 * Ok we have prepared all new packfiles.
 	 * First see if there are packs of the same name and if so