tests: stablize test-serve.t on Windows...
tests: stablize test-serve.t on Windows
I forget the reason that the subprocess on Windows doesn't print this, but all
other instances of this are similarly conditionalized, so I didn't think too
hard about it.
Also, the server needs to be killed so it doesn't prevent the next run from
working, especially since the port isn't randomized.
Differential Revision:
https://phab.mercurial-scm.org/D8720
