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 foo
adding bomb
adding a.c
adding dir/a.o
adding dir/b.o
! a.c
! dir/a.o
! dir/b.o
? .hgignore
a.c: unsupported file type (type is fifo)
! a.c