[Groff] strange defining of undefined names

[Bernd Warken]

There is a strange anomaly about undefined names in commented/ignored
environments.  Try the following roff fragments:

1.
.rm s
.\" comment on \*[s]
.ie d s .tm yes
.el .tm no

This prints `no'; that's ok.


2.
.rm s
\c comment on \*[s]
.ie d s .tm yes
.el .tm no

This prints `yes' - strange.


3.
.rm s
.ig
comment on \*[s]
..
.ie d s .tm yes
.el .tm no

This prints `yes' - strange.


4.
.de c
..
.rm s
.c comment on \*[s]
.ie d s .tm yes
.el .tm no

This prints `yes' - strange.