[MERGE] fix blackbox failures when run from windows executable

[Adrian Wilkins]

Alexander Belchenko wrote:
> I have strong opinion that bzr.exe should be distributed without test
suite.

I concur on this point ; process creation overhead on Windows is large
enough, which is one of the reasons why git is (IMHO) less practical on
Windows than bzr. I've had instances where I've written a small *nix
style tool to process large numbers of files, and running it through a
shell pipeline on Windows over half the runtime is consumed by process
startup and teardown.

> And because these problems stays here for years, fixing test suite
should not be high priority. Mostly because test suite on Windows don't
running regularly opposing to PQM

I see the inverse of this point ; part of the reason there is little
incentive to set up a Windows test server for PQM is that the test suite
has so many failures on Windows. This means that rather than just
checking that failures == 0, you have to specifically check what failed,
whether known (but not expected) failures failed in a different way to
last time, etc. This makes writing a useful automated PQM gatekeeper for
Windows tests much harder, which is a huge disincentive to actually set
one up. If the test suite passed on Windows, that important link in the
quality chain has one less reason to be absent.