[PATCH] tests: actually restore the original environment before running syshg

[Adam Simpkins]

On Jun 30, Yuya Nishihara wrote:
> # HG changeset patch
> # User Yuya Nishihara <yuya at tcha.org>
> # Date 1498826969 -32400
> #      Fri Jun 30 21:49:29 2017 +0900
> # Node ID fe3419b41a456661a3d35ae963d06a203d4446a2
> # Parent  40ee74bfa11122a0a3ab74186f5056243b84af89
> tests: actually restore the original environment before running syshg
> 
> Since os.environ may be overridden in run-tests.py, several important
> variables such as PATH weren't restored.
> 
> I don't like the idea of using the system hg *by default* because the
> executable and the configs are out of our control. But I don't mind as
> long as the tests pass.

Thanks for helping track down and fix the issue!  This diff looks good
to me.

-- 
Adam Simpkins
simpkins at fb.com