tree b237d98bb33622718431de5f4a76a60b85f26245
parent 6623b21e1073a70f7d5cc6eddd364bdab337b439
author Roy Lee <roylee17@gmail.com> 1273350728 +0800
committer Shawn O. Pearce <sop@google.com> 1274997260 -0700

sync: support --jobs to fetch projects simultaneously

This patch does two things for being compatibile with
those Python which are built without threading support:

1. As the Python document and Shawn suggested, import dummy_threading
   when the threading is not available.

2. Reserve the single threaded code and make it default.
   In cases the --jobs does not work properly with dummy_threading,
   we still have a safe fallback.

Change-Id: I40909ef8e9b5c22f315c0a1da9be38eed8b0a2dc