Ex2fs_unlink() will return an error if both the name and inode number are

Ex2fs_unlink() will return an error if both the name and inode number are
unspecified, to avoid doing something surprising (such as unconditionally
deleting the first directory entry).   Directory entries are now deleted
by coalescing them with the previous directory entry if possible, to
avoid directory fragmentation.  This is not an issue with the e2fsprogs suite,
but may be a problem for some of the users of libext2fs, such as e2tools.