Summary:
The helper could be used in individual tests to enable chg if chg exists.
This allows us to have more precise control on what tests to use chg instead
of using a global flag in run-tests.py.
This makes certain tests containing many hg commands much faster. For example,
`test-revset.t` took 99 seconds before:
% ./run-tests.py test-revset.t --time
.
# Ran 1 tests, 0 skipped, 0 failed.
# Producing time report
start end cuser csys real Test
0.000 99.990 86.410 12.000 99.990 test-revset.t
And 10 seconds after:
% ./run-tests.py test-revset.t --time
.
# Ran 1 tests, 0 skipped, 0 failed.
# Producing time report
start end cuser csys real Test
0.000 10.080 0.380 0.130 10.080 test-revset.t
Also enable it for some other tests. Note the whitelist is not complete. We
probably want to whitelist more tests in the future.
The feature could be opted out by deleting `contrib/chg/chg`.
Reviewed By: phillco
Differential Revision: D6767036
fbshipit-source-id: 8220cf408aa198d5d8e2ca5127ca60e2070d3444