[MERGE] More than double the speed of "bzr selftest"

[Andrew Bennetts]

John Arbash Meinel wrote:
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> Martin Pool wrote:
> > Here's my overall bundle for this.  It takes it further than Andrew
> > did, removing --keep-output and always storing the test directories in
> > TMPDIR, which makes things faster overall.
> > 
> 
> I just ran into a problem with this. You are using "atexit()" to register a
> cleanup function.
> 
> However, 'bzr' the front-end uses 'os._exit()' rather that sys.exit because we
> don't feel like wasting time cleaning up after ourselves.
[...]
> 
> But that means that atexit() no longer runs, so we won't be cleaning up our
> temporary directories.

Good catch.

> To fix this, I think we can just extend our TestSuiteRunner so that we can
> setup things for it to run after everything is done.

Even simpler: call sys.exitfunc() just before calling os._exit().

-Andrew.