hgmerge: do not use file with markers in tools merging themselves
This time I forgot about a crucial part of the logic change.
The patch makes kdiff3 and tkdiff useful again.
adding aadding baNONEXISTENT: No such file or directoryaba: No such file or directoryNONEXISTENT: No such file or directorybaNONEXISTENT: No such file in rev 9e1684505872ab