Merge branch 'kg/gc-auto-windows-workaround' into pu

"git gc --auto" opens file descriptors for the packfiles before
spawning "git repack/prune", which would upset Windows that does
not want a process to work on a file that is open by another
process.  The issue has been worked around.

* kg/gc-auto-windows-workaround:
  gc --auto: release pack files before auto packing

Author: gitster

builtin/gc.c

@@ -616,6 +616,7 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 		return -1;
 
 	if (!repository_format_precious_objects) {
+		close_all_packs(the_repository->objects);
 		if (run_command_v_opt(repack.argv, RUN_GIT_CMD))
 			return error(FAILED_RUN, repack.argv[0]);
 

t/t5510-fetch.sh

@@ -828,9 +828,11 @@ test_expect_success 'fetching with auto-gc does not lock up' '
 	test_commit test2 &&
 	(
 		cd auto-gc &&
+		git config fetch.unpackLimit 1 &&
 		git config gc.autoPackLimit 1 &&
 		git config gc.autoDetach false &&
 		GIT_ASK_YESNO="$D/askyesno" git fetch >fetch.out 2>&1 &&
+		test_i18ngrep "Auto packing the repository" fetch.out &&
 		! grep "Should I try again" fetch.out
 	)
 '