Fix upstream.sh presubmit test for git 1.8.3+

tests/test-lib.sh

 #!/bin/bash
 
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Abort on error.
 set -e
 
 export DEPOT_TOOLS_UPDATE=0
@@ skipping 31 matching lines @@
 
   svn cp -q -m 'branching' --parents $TRUNK_URL $BRANCH_URL
 }
 
 # Set up a git-svn checkout of the repo.
 setup_gitsvn() {
   echo "Setting up test git-svn repo..."
   rm -rf git-svn
   # There appears to be no way to make git-svn completely shut up, so we
   # redirect its output.
-  git svn -q clone -s $REPO_URL git-svn >/dev/null 2>&1
+  git svn --prefix origin/ -q clone -s $REPO_URL git-svn >/dev/null 2>&1
   (
     cd git-svn
+    git remote add origin https://example.com/fake_refspec
     git config user.name 'TestDood'
     git config user.email 'TestDood@example.com'
   )
 }
 
 # Set up a git-svn checkout of the repo and apply merge commits
 # (like the submodule repo layout).
 setup_gitsvn_submodule() {
   echo "Setting up test remote git-svn-submodule repo..."
   rm -rf git-svn-submodule
@@ skipping 75 matching lines @@
     return $exit_code
   fi
 }
 
 # Grab the XSRF token from the review server and print it to stdout.
 print_xsrf_token() {
   curl --cookie dev_appserver_login="test@example.com:False" \
     --header 'X-Requesting-XSRF-Token: 1' \
     http://localhost:8080/xsrf_token 2>/dev/null
 }