Add 'fetch' command to gclient with support for --jobs.

gclient.py

Index: gclient.py
===================================================================
--- gclient.py	(revision 123383)
+++ gclient.py	(working copy)
@@ -1166,6 +1166,22 @@
   return 0
 
 
+def CMDfetch(parser, args):
+  """Fetches upstream commits for all modules.
+
+Completely git-specific. Simply runs 'git fetch origin' for each module.
+"""
+  parser.remove_option('--jobs')

[M-A Ruel, 2012/02/27 16:52:48]

It's useful and safe to do them in parallel. I'd keep --jobs.

+  (options, parsed_args) = parser.parse_args(args)

[M-A Ruel, 2012/02/27 16:52:48]

Why parse the arguments here? Just forward the modified args directly to
CMDrecurse?

+  if parsed_args:
+    print >> sys.stderr, 'Fetch accepts no arguments!'
+    return 1
+  args.extend('-s git git fetch origin'.split(' '))

[M-A Ruel, 2012/02/27 16:52:48]

Let's do
args = ['-s', 'git', 'git', 'fetch'] + args
so origin is not specified by default, so people with multiple remote have all
the remote fetched by default and that specifying a remote work properly, e.g.
gclient fetch origin
works intuitively.

+  # Add jobs option back, so CMDrecurse doesn't freak.
+  parser.add_option('--jobs')
+  return CMDrecurse(parser, args)
+
+
 @attr('usage', '[url] [safesync url]')
 def CMDconfig(parser, args):
   """Create a .gclient file in the current directory.