Minor fix for revert: No need to make a backup when forgetting added files.
echo foo > foo && hg add foo && hg revert foo
creates foo.orig, though foo is not changed or deleted.
adding aadding baNONEXISTENT: No such file or directoryaba: No such file or directoryNONEXISTENT: No such file or directorybaNONEXISTENT: No such file in rev 14467d15ef43ab