That pesky windows run-tests failure on the buildbot

[Matt Harbison]

> On Dec 12, 2017, at 5:57 PM, Augie Fackler <raf at durin42.com> wrote:
> 
> Finally, some useful output:
> 
> +  --- $TESTTMP/anothertests/test-runtestdir.t
> +  +++ $TESTTMP/anothertests/test-runtestdir.t.err
> +  @@ -10,6 +10,7 @@
> +   If this prints a path, that means RUNTESTDIR didn't equal
> +   TESTDIR as it should have.
> +     $ test "$RUNTESTDIR" = "G:\Users\test\projects\hg-default-x86_64\Win7_x86_64_hg_tests\build\tests" || echo "$RUNTESTDIR"
> +  +  g:\Users\test\projects\hg-default-x86_64\Win7_x86_64_hg_tests\build\tests
> 
> Basically, it's failing because one of os.path.{abspath,dirname} is deciding to lowercase the drive letter. I suspect it's abspath, but I don't have a Windows machine handy to test against. Anyone got a clever idea on how to fix this?

The odd thing is, this runs fine on this machine from this directory when not under buildbot.  Nothing in the environment looked out or place, so idk why that happens.