There is now a separate XP-compatible release which doesn't have
the performance fix for index-pack.

BUG=
NOTRY=true
R=mmoss@google.com

Review URL: https://codereview.chromium.org/215133002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@260010 0039d316-1c4b-4281-b951-d872f2087c98