This PR addresses two rare but occasional test failures on windows, both
due to window's non-synchronous file system behavior.
- A race condition opening the local test database causing an error.
- Unwanted cleanup conditions in testing the log preservation can
trigger if the test execution is stretched out long enough.
- A null-termination bug in set_file_metadata that causes it to fail
silently if the memory layout is such a way that the string passed in
isn't null-terminated. This causes occasional failures in setting the
metadata time on linux.