Karsten Loesing authored Dec 16, 2020 and Nick Mathewson committed Dec 21, 2020

The previous parser only considered stats files _starting_ with the
timestamp tag, not stats files having the timestamp tag in a later
position. While this applies to all current stats files, a future
stats file might look differently. Better to fix the function now than
be surprised in another 9 years from now.

This commit also adds a test case for such future stats, and it fixes
stats file paths in newly added unit tests.