Bug#4035 - HiddenStores file not renamed every time.
Adding regression tests for the behavior reported in Bug#4035, and tweaking
the code to handle these cases.
Added more regression tests, and tweaked code to add more logging, and to
handle additional error cases.  This should help remove edge cases where
HiddenStores are not properly deleted on error.
More fixes/tweaks for Bug#4035.
Merge pull request #53 from proftpd/xfer-hiddenstores-not-renamed-bug4035

Bug#4035 - HiddenStores file not renamed every time