Re-try deleting working files in is_run
Re-try deleting working files in is_run

It appears on Windows, when the `is_run` code launches it's own Proc
that does STDIN things, there's some delay before `.in` file can
be deleted by `is_run` so if we detect failurage to delete a working
file, before dying, sleep a bit and retry and only if we fail then,
then die.

dogbert17/roast,dogbert17/roast,bitrauser/roast,bitrauser/roast,perl6/roast