rename_tmp_log(): limit the number of remote_empty_directories() attempts

This doesn't seem to be a likely error, but we've got the counter
anyway, so we might as well use it for an added bit of safety.

Please note that the first call to rename() is optimistic, and it is
normal for it to fail if there is a directory in the way.  So bump the
total number of allowed attempts to 4, to be sure that we can still
have at least 3 retries in the case of a race.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

refs.c

@@ -2530,7 +2530,7 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
 
 static int rename_tmp_log(const char *newrefname)
 {
-	int attempts_remaining = 3;
+	int attempts_remaining = 4;
 
  retry:
 	if (safe_create_leading_directories(git_path("logs/%s", newrefname))) {
@@ -2539,7 +2539,7 @@ static int rename_tmp_log(const char *newrefname)
 	}
 
 	if (rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
-		if (errno==EISDIR || errno==ENOTDIR) {
+		if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
 			/*
 			 * rename(a, b) when b is an existing
 			 * directory ought to result in ISDIR, but