tests: add optional output when wheel is missing
If the `wheel` package isn't installed, pip will emit a warning
on stderr complaining about that. Alternatively, we could
redirect stderr to stdout and swallow the warning. But I like
tests having visibility of warnings, as it helps keep us honest
regarding edge cases.
Differential Revision: https://phab.mercurial-scm.org/D7371
@echo off
powershell -NoProfile -ExecutionPolicy unrestricted -Command "& '%~dp0\editmergeps.ps1' %*"