The script will poll the remote branch until the git updater
has replicated the commit to tag. The tag will then be
directly pushed to git.

BUG=chromium:410721
LOG=n
TEST=script_test.py
R=agable@chromium.org, tandrii@chromium.org
TBR=tandrii@chromium.org

Review URL: https://codereview.chromium.org/607893004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24431 ce2b1a6d-e550-0410-aec6-3dcde31c8c00