fix handling of files of unsupported type in the walk code
if a file was of unsupported type, it was considered as 'seen' while
walking. this way it was possible to have file in the dirstate not
yielded by the walk function.
bar: unsupported file type (type is symbolic link)
adding foo
bar: unsupported file type (type is symbolic link)
bar: unsupported file type (type is symbolic link)
adding bomb
bar: unsupported file type (type is symbolic link)
adding a.c
adding dir/a.o
adding dir/b.o
a.c: unsupported file type (type is fifo)
dir/b.o: unsupported file type (type is symbolic link)
R a.c
R dir/a.o
R dir/b.o
? .hgignore