fix windows transfer lock check

fix windows transfer lock check

If the lock file was not able to be exclusivlely locked, don't indicate
locking failed. I'm pretty sure this was a typo. It goes all the way
back to 891c85cd88c5a90daf7d18160eeddd1483e8c649 where locking was first
introduced on windows, and there's no indication of why it would make
sense to return True here.

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