aborted reverify restores file owner and permission

aborted reverify restores file owner and permission

If we get an IMS hit for an InRelease file we use the file we already
have and pass it into reverification, but this changes the permissions
and on abort of the transaction they weren't switched back.

This is now done, additionally, every file in partial which hasn't
failed gets permission and owner changed for root access as well, as it
is very well possible that the next invocation will (re)use these files.