Wall broken with sysutils/screen

Revision 1.12 of src/usr.bin/wall/ttymsg.c seems to have broken
wall with screen.

If I have users logged in running screen, then wall fails to
write to their terminals, giving errors such as "Too many
'/' in "/dev/pts//0"".

I don't really know why that / is doubled, but it is doubled
for every user running screen.

Frobbing kern.pts.enable doesn't seem to make any difference.

Ceri
-- 
That must be wonderful!  I don't understand it at all.
                                                   -- Moliere