also fix reference deletion

Author: ericLemanissier

services/mirror/mirror_pull.go

@@ -129,7 +129,12 @@ func parseRemoteUpdateOutput(output, remoteName string) []*mirrorSyncResult {
 			if isTag {
 				refFullName = git.RefNameFromTag(refName)
 			} else {
-				refFullName = git.RefNameFromBranch(strings.TrimPrefix(refName, remoteName+"/"))
+				var refFullName git.RefName
+				if strings.HasPrefix(refName, "refs/") {
+					refFullName = git.RefName(refName)
+				} else {
+					refFullName = git.RefNameFromBranch(strings.TrimPrefix(refName, remoteName+"/"))
+				}
 			}
 			results = append(results, &mirrorSyncResult{
 				refName:     refFullName,