name-rev: avoid leaking memory in the deref case

When the `name_rev()` function is asked to dereference the tip name, it
allocates memory. But when it turns out that another tip already
described the commit better than the current one, we forgot to release
the memory.

Pointed out by Coverity.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

builtin/name-rev.c

@@ -28,14 +28,15 @@ static void name_rev(struct commit *commit,
 	struct rev_name *name = (struct rev_name *)commit->util;
 	struct commit_list *parents;
 	int parent_number = 1;
+	char *to_free = NULL;
 
 	parse_commit(commit);
 
 	if (commit->date < cutoff)
 		return;
 
 	if (deref) {
-		tip_name = xstrfmt("%s^0", tip_name);
+		tip_name = to_free = xstrfmt("%s^0", tip_name);
 
 		if (generation)
 			die("generation: %d, but deref?", generation);
@@ -53,8 +54,10 @@ static void name_rev(struct commit *commit,
 		name->taggerdate = taggerdate;
 		name->generation = generation;
 		name->distance = distance;
-	} else
+	} else {
+		free(to_free);
 		return;
+	}
 
 	for (parents = commit->parents;
 			parents;