Attempt to fix the Travis docs builds.
Review Request #7599 — Created Aug. 17, 2015 and submitted — Latest diff uploaded
The Travis docs builds were broken for two reasons. First, we were using a function not available on Python 2.6 (subprocess.check_output), and second, we were assuming a full Git tree with a master branch (needed for linking code). The check_output call has been replaced with a more direct Popen request, and the build file now explicitly fetches the master branch.
I reproduced the problems locally, and this fixed them both. I haven't tested
on Travis yet.