Add quotes around command line in subproccess error message

tests/gclient_smoketest.py

 #!/usr/bin/env python
 # 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.
 
 """Smoke tests for gclient.py.
 
 Shell out 'gclient' and run basic conformance tests.
 
 This test assumes GClientSmokeBase.URL_BASE is valid.
@@ skipping 499 matching lines @@
     self.assertTree(tree)
 
   def testPreDepsHooksError(self):
     if not self.enabled:
       return
     self.gclient(['config', self.git_base + 'repo_5', '--name', 'src'])
     expectated_stdout = [
         ('running', self.root_dir),                 # pre-deps hook
         ('running', self.root_dir),                 # pre-deps hook (fails)
     ]
-    expected_stderr = ('Error: Command /usr/bin/python -c import sys; '
-                       'sys.exit(1) returned non-zero exit status 1 in %s\n'
+    expected_stderr = ("Error: Command '/usr/bin/python -c import sys; "
+                       "sys.exit(1)' returned non-zero exit status 1 in %s\n"
                        % self.root_dir)
     stdout, stderr, retcode = self.gclient(['sync', '--deps', 'mac', '--jobs=1',
                                             '--revision',
                                             'src@' + self.githash('repo_5', 3)])
     self.assertEquals(stderr, expected_stderr)
     self.assertEquals(2, retcode)
     self.checkBlock(stdout, expectated_stdout)
 
   def testRevInfo(self):
     if not self.enabled:
@@ skipping 374 matching lines @@
 
   if '-c' in sys.argv:
     COVERAGE = True
     sys.argv.remove('-c')
     if os.path.exists('.coverage'):
       os.remove('.coverage')
     os.environ['COVERAGE_FILE'] = os.path.join(
         os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
         '.coverage')
   unittest.main()