Enable implicit auto-upgrade to python 2.7.5.
Enable implicit auto-upgrade to python 2.7.5.

This will automatically upgrade python to 2.7.5 unless
set DEPOT_TOOLS_PYTHON_275=0
is used.

R=iannucci@chromium.org
BUG=241769

Review URL: https://codereview.chromium.org/53313002

git-svn-id: bd64dd6fa6f3f0ed0c0666d1018379882b742947@235140 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

svn2github/chromium-depot-tools,svn2github/chromium-depot-tools,svn2github/chromium-depot-tools