Found and squashed a nasty bug where file_copy() was defaulted to ignore errors. There was also an issue in file_exists() that was causing the test to fail when the file actually did exist. Together they could have resulted in a corrupt backup with no errors, though it is very unlikely.

Worked on improving error handling in the File object. This is not complete, but works well enough to find a few errors that have been causing us problems (notably, find is occasionally failing building the archive async manifest when system is under load).