Make syzygy recipes explicitly set GIT_MODE

scripts/slave/recipes/syzygy/smoke_test.py

 # Copyright 2014 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.
 
 """Buildbot recipe definition for the various Syzygy Smoke Test builder.
 
 To be tested using a command-line like:
 
   /build/scripts/tools/run_recipe.py syzygy/continuous
       revision=0e9f25b1098271be2b096fd1c095d6d907cf86f7
@@ skipping 28 matching lines @@
 
 def RunSteps(api, buildername):
   """Generates the sequence of steps that will be run on the coverage bot."""
   assert buildername == 'Syzygy Smoke Test'
 
   # Configure the build environment.
   s = api.syzygy
   kwargs = {'BUILD_CONFIG': 'Release'}
   s.set_config('syzygy', **kwargs)
   api.chromium.set_config('syzygy', **kwargs)
-  api.gclient.set_config('syzygy', **kwargs)
+  api.gclient.set_config('syzygy', GIT_MODE=True, **kwargs)
 
   # Clean up any running processes on the slave.
   s.taskkill()
 
   # Checkout and compile the project.
   s.checkout()
   s.runhooks()
 
   s.download_binaries()
   s.smoke_test()
 
 
 def GenTests(api):
   """Generates an end-to-end successful test for this builder."""
   yield api.syzygy.generate_test(api, 'Syzygy Smoke Test')