bug#3811: 23.0.96; custom-group-members

emacs -Q
 
Dunno if this is just a doc bug or a code bug. `custom-group-members'
seems to give the same result - a list of groups, whether its second
arg GROUPS-ONLY is nil or t. I don't see any difference.
 
Even if there are some cases where there would be a difference, the
doc string is unclear, because it doesn't say what the alternative
is. What should you expect if GROUPS-ONLY is nil, other than groups?
What else might be included in the list?
 
FWIW, I was looking for a function that, given a group, would return a
list of all options and faces in that group (directly, not by
inheritance). From the function name and doc string, I thought perhaps
`custom-group-members' would do the job (with a nil arg). Apparently
not. But I don't know what it is _supposed_ to do when GROUPS-ONLY is
nil.
 

In GNU Emacs 23.0.96.1 (i386-mingw-nt5.1.2600)
 of 2009-07-09 on SOFT-MJASON
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4)'