Re: [RFC PATCH] rerere: fix overeager gc

[Johannes Sixt <j.sixt@viscovery.net>]

Instead of this series, I'll use this for a while; i.e., check the
timestamp of thisimage, and if it does not exist, check the directory's
timestamp. It doesn't pass t4200.20 because the test doesn't set the
timestamps of thisimage and the directory into the past.

diff --git a/builtin/rerere.c b/builtin/rerere.c
index 980d542..49fcbf7 100644
--- a/builtin/rerere.c
+++ b/builtin/rerere.c
@@ -13,10 +13,14 @@ static const char git_rerere_usage[] =
 static int cutoff_noresolve = 15;
 static int cutoff_resolve = 60;
 
-static time_t rerere_created_at(const char *name)
+static time_t rerere_last_used_at(const char *name)
 {
 	struct stat st;
-	return stat(rerere_path(name, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
+	if (!stat(rerere_path(name, "thisimage"), &st))
+		return st.st_mtime;
+	if (errno == ENOENT && !stat(rerere_path(name, "."), &st))
+		return st.st_mtime;
+	return (time_t) 0;
 }
 
 static void unlink_rr_item(const char *name)
@@ -53,7 +57,7 @@ static void garbage_collect(struct string_list *rr)
 	while ((e = readdir(dir))) {
 		if (is_dot_or_dotdot(e->d_name))
 			continue;
-		then = rerere_created_at(e->d_name);
+		then = rerere_last_used_at(e->d_name);
 		if (!then)
 			continue;
 		cutoff = (has_rerere_resolution(e->d_name)