The hashserve can delete its socket whilst the cleanup us happening leading to
backtraces and test failures.
Add code to avoid this race condition.
[YOCTO #13542]
(Bitbake rev: efd7b025cee25d0ee668c09476395d08fcf5ae1a)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>