Allow clobbering of existing tags from remote.

Bug: 120778183
Change-Id: Id44e2b68abc410a3afd4e07a3c943b0936347e38
diff --git a/repo b/repo
index 998731c..7e7f13f 100755
--- a/repo
+++ b/repo
@@ -536,7 +536,7 @@
     err = None
   cmd.append(src)
   cmd.append('+refs/heads/*:refs/remotes/origin/*')
-  cmd.append('refs/tags/*:refs/tags/*')
+  cmd.append('+refs/tags/*:refs/tags/*')
 
   proc = subprocess.Popen(cmd, cwd=local, stderr=err)
   if err: