The way this option worked was, if enabled (and it was off by default), bit 7
of all character input *before* successful logon would be stripped and bit 7
from all character input of terminals configured as US-ASCII (only) would be
stripped after logon.

Instead, always strip bit 7 (the 8th bit) of each input character from US-ASCII
(only) terminals. Other detected/configured terminals (CP437, UTF-8, PETSCII)
won't have bit 7 stripped (ever) since that's likely not a necessary or nice
thing to do. There's now no different handling of pre/post logon in this
regard.

If there's a need to strip parity bits from character input from client
terminals that support CP437, UTF-8, or PETSCII, then we'll re-add this feature
in but it shouldn't be a per-node setting in that case.