[Groff] tbl bug

[Konovalov, Vadim]

Hello.

following table:
.TS
allbox tab(;);
cs
cs.
a
.T&
cs
cc.
a
a;b
.TE

is processed differently by groff-tbl and troff-tbl. Namely, after .T&
groff-tbl "remembers" one extra format line that was seen before, so
"logically" that table looks like following:
.TS
allbox tab(;);
cs.
a
.T&
cs
cs
cc.
a
a;b
.TE
and tbl preprocessor explains that "excess data entry 'b' is discarded".

troff's tbl preprocessor "resets" all elder format specification when it
.T& and this approach seems to be more sane for me.

Is this is a bug or (mis)feature?
How should I fix it?

I'm using groff-1.11a, and tried 1.15; they behave exactly the same way in
my case.

Good luck,
Vadim.