Revert parallel checkout as the default.

This is because buildbot can't parse gclient output with parallel checkout,
causing got_revision to not be set, causing some scripts to fail.

TBR=bradnelson
TEST=none
BUG=none

Review URL: http://codereview.chromium.org/3325023

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@59121 0039d316-1c4b-4281-b951-d872f2087c98

gclient.py

@@ -1175,7 +1175,7 @@ def Main(argv):
         '  %-10s %s' % (fn[3:], Command(fn[3:]).__doc__.split('\n')[0].strip())
         for fn in dir(sys.modules[__name__]) if fn.startswith('CMD')]))
     parser = optparse.OptionParser(version='%prog ' + __version__)
-    parser.add_option('-j', '--jobs', default=8, type='int',
+    parser.add_option('-j', '--jobs', default=1, type='int',
                       help='Specify how many SCM commands can run in parallel; '
                            'default=%default')
     parser.add_option('-v', '--verbose', action='count', default=0,