Improve duplicate detection and repo_move_valid

Improve duplicate detection and repo_move_valid

Only trigger a duplicate error if a valid filepath is revisted. It is
possible that a bad CA references somebody else's files and if that
happens first it would block the valid access.

To make this work, pass the ok flag to filepath_add() and only set the
talmask bit if the file was ok. Since we need to do the duplicate check
before processing the entity introduce filepath_valid() which checks
if the path is in the tree and has its talmask bit set.

In repo_move_valid() handle conflicts more gracefully. When both a valid
and temporary file are present assume that one of the files was never ok
(talmask == 0) and silently remove that file from the filepath tree.

OK tb@