add_reflog_for_walk: avoid memory leak

We free()d the `log` buffer when dwim_log() returned 1, but not when it
returned a larger value (which meant that it still allocated the buffer
but we simply ignored it).

While in the vicinity, make sure that the `reflogs` structure as well as
the `branch` variable are released properly, too.

Identified by Coverity.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

reflog-walk.c

@@ -183,7 +183,11 @@ int add_reflog_for_walk(struct reflog_walk_info *info,
 		if (!reflogs || reflogs->nr == 0) {
 			struct object_id oid;
 			char *b;
-			if (dwim_log(branch, strlen(branch), oid.hash, &b) == 1) {
+			int ret = dwim_log(branch, strlen(branch),
+					   oid.hash, &b);
+			if (ret > 1)
+				free(b);
+			else if (ret == 1) {
 				if (reflogs) {
 					free(reflogs->ref);
 					free(reflogs);
@@ -193,17 +197,27 @@ int add_reflog_for_walk(struct reflog_walk_info *info,
 				reflogs = read_complete_reflog(branch);
 			}
 		}
-		if (!reflogs || reflogs->nr == 0)
+		if (!reflogs || reflogs->nr == 0) {
+			if (reflogs) {
+				free(reflogs->ref);
+				free(reflogs);
+			}
+			free(branch);
 			return -1;
+		}
 		string_list_insert(&info->complete_reflogs, branch)->util
 			= reflogs;
 	}
+	free(branch);
 
 	commit_reflog = xcalloc(1, sizeof(struct commit_reflog));
 	if (recno < 0) {
 		commit_reflog->recno = get_reflog_recno_by_time(reflogs, timestamp);
 		if (commit_reflog->recno < 0) {
-			free(branch);
+			if (reflogs) {
+				free(reflogs->ref);
+				free(reflogs);
+			}
 			free(commit_reflog);
 			return -1;
 		}