Don't abort when backup files already exist. Don't allow alternative names. Rationale: - When the user wants to revert, he shouldn't be stopped from doing this just because some old backups will be overwritten. - To not clobber important files by accident, alternative names for backup files were disabled. As the backup target now has a fixed name, the user doesn't have to be informed about the backup copy (unless --verbose)

removing b
this update spans a branch affecting the following files:
 b
aborting update spanning branches!
(use 'hg merge' to merge across branches or '-C' to lose changes)