Merge branch 'js/close-packs-before-gc' into maint

Many codepaths that run "gc --auto" before exiting kept packfiles
mapped and left the file descriptors to them open, which was not
friendly to systems that cannot remove files that are open.  They
now close the packs before doing so.

* js/close-packs-before-gc:
  receive-pack: release pack files before garbage-collecting
  merge: release pack files before garbage-collecting
  am: release pack files before garbage-collecting
  fetch: release pack files before garbage-collecting

builtin/am.c

@@ -1939,6 +1939,7 @@ static void am_run(struct am_state *state, int resume)
 	 */
 	if (!state->rebasing) {
 		am_destroy(state);
+		close_all_packs();
 		run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 	}
 }

builtin/fetch.c

@@ -1221,6 +1221,8 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
 	list.strdup_strings = 1;
 	string_list_clear(&list, 0);
 
+	close_all_packs();
+
 	argv_array_pushl(&argv_gc_auto, "gc", "--auto", NULL);
 	if (verbosity < 0)
 		argv_array_push(&argv_gc_auto, "--quiet");

builtin/merge.c

@@ -404,6 +404,7 @@ static void finish(struct commit *head_commit,
 			 * We ignore errors in 'gc --auto', since the
 			 * user should see them.
 			 */
+			close_all_packs();
 			run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 		}
 	}

builtin/receive-pack.c

@@ -1796,6 +1796,7 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 				"gc", "--auto", "--quiet", NULL,
 			};
 			int opt = RUN_GIT_CMD | RUN_COMMAND_STDOUT_TO_STDERR;
+			close_all_packs();
 			run_command_v_opt(argv_gc_auto, opt);
 		}
 		if (auto_update_server_info)

t/t5510-fetch.sh

@@ -708,4 +708,17 @@ test_expect_success 'fetching a one-level ref works' '
 	)
 '
 
+test_expect_success 'fetching with auto-gc does not lock up' '
+	write_script askyesno <<-\EOF &&
+	echo "$*" &&
+	false
+	EOF
+	git clone "file://$D" auto-gc &&
+	test_commit test2 &&
+	cd auto-gc &&
+	git config gc.autoPackLimit 1 &&
+	GIT_ASK_YESNO="$D/askyesno" git fetch >fetch.out 2>&1 &&
+	! grep "Should I try again" fetch.out
+'
+
 test_done