Testing on a bot with an 'unclean' Chromium checkout:

Unpatched `gclient revert -v -v -v --nohooks --upstream` (unclean checkout)
real    9m14.280s
user    0m37.238s
sys     0m37.738s

Patched 'gclient revert -v -v -v --nohooks --upstream'  (unclean checkout)
real    5m50.065s
user    1m18.889s
sys     0m57.860s

---------------- after patched gclient revert run (cleans the checkout)

Unpatched 'gclient revert -v -v -v --nohooks --upstream' (clean checkout)
real    0m21.602s
user    0m24.966s
sys     0m13.969s

Patched 'gclient revert -v -v -v --nohooks --upstream' (clean checkout)
real    0m27.467s
user    0m28.382s
sys     0m22.629s

BUG=336983

Review URL: https://codereview.chromium.org/240503007

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@264753 0039d316-1c4b-4281-b951-d872f2087c98