remote: clear string_list after use in mv()

Switch to the _DUP variant of string_list for remote_branches to allow
string_list_clear() to release the allocated memory at the end, and
actually call that function.  Free the util pointer as well; it is
allocated in read_remote_branches().

NB: This string_list is empty until read_remote_branches() is called
via for_each_ref(), so there is no need to clean it up when returning
before that point.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/remote.c

@@ -565,7 +565,7 @@ static int read_remote_branches(const char *refname,
 
 	strbuf_addf(&buf, "refs/remotes/%s/", rename->old_name);
 	if (starts_with(refname, buf.buf)) {
-		item = string_list_append(rename->remote_branches, xstrdup(refname));
+		item = string_list_append(rename->remote_branches, refname);
 		symref = resolve_ref_unsafe(refname, RESOLVE_REF_READING,
 					    NULL, &flag);
 		if (symref && (flag & REF_ISSYMREF))
@@ -611,7 +611,7 @@ static int mv(int argc, const char **argv)
 	struct remote *oldremote, *newremote;
 	struct strbuf buf = STRBUF_INIT, buf2 = STRBUF_INIT, buf3 = STRBUF_INIT,
 		old_remote_context = STRBUF_INIT;
-	struct string_list remote_branches = STRING_LIST_INIT_NODUP;
+	struct string_list remote_branches = STRING_LIST_INIT_DUP;
 	struct rename_info rename;
 	int i, refspec_updated = 0;
 
@@ -733,6 +733,7 @@ static int mv(int argc, const char **argv)
 		if (create_symref(buf.buf, buf2.buf, buf3.buf))
 			die(_("creating '%s' failed"), buf.buf);
 	}
+	string_list_clear(&remote_branches, 1);
 	return 0;
 }