Make git auto-svn fail if git svn fetch fails.

tests/git_common_test.py

 #!/usr/bin/env python
 # Copyright 2013 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.
 
 """Unit tests for git_common.py"""
 
 import binascii
 import collections
 import os
@@ skipping 203 matching lines @@
     items = set(self.repo.commit_map.itervalues())
 
     def testfn():
       for line in self.gc.run_stream('log', '--format=%H').xreadlines():
         line = line.strip()
         self.assertIn(line, items)
         items.remove(line)
 
     self.repo.run(testfn)
 
+  def testStreamWithRetcode(self):
+    items = set(self.repo.commit_map.itervalues())
+
+    def testfn():
+      with self.gc.run_stream_with_retcode('log', '--format=%H') as stdout:
+        for line in stdout.xreadlines():
+          line = line.strip()
+          self.assertIn(line, items)
+          items.remove(line)
+
+    self.repo.run(testfn)
+
+  def testStreamWithRetcodeException(self):
+    import subprocess2
+    with self.assertRaises(subprocess2.CalledProcessError):
+      with self.gc.run_stream_with_retcode('checkout', 'unknown-branch'):
+        pass
+
   def testCurrentBranch(self):
     def cur_branch_out_of_git():
       os.chdir('..')
       return self.gc.current_branch()
     self.assertIsNone(self.repo.run(cur_branch_out_of_git))
 
     self.repo.git('checkout', 'branch_D')
     self.assertEqual(self.repo.run(self.gc.current_branch), 'branch_D')
 
   @unittest.skip('broken by git 2.4')
@@ skipping 493 matching lines @@
       self.assertEquals(self.repo.git('status', '--porcelain').stdout, STATUS_1)
 
     self.repo.run(inner)
 
 
 if __name__ == '__main__':
   sys.exit(coverage_utils.covered_main(
     os.path.join(DEPOT_TOOLS_ROOT, 'git_common.py'),
     required_percentage=88.0
   ))