bug#5284: 23.1; gnus-summary-expire-thread does not work

[Andreas Seltenreich]

Tom Tromey writes:

> I tried "T E" (gnus-summary-expire-thread) in an nnml group.
> The thread disappeared from the summary buffer -- not quite what I
> expected, but reasonable enough.
> Then I left the group with "q" and re-entered it.
> The thread was still there.
> I expected all the messages in the thread to be expired.

I fixed this in the Gnus repository.  I'll leave this bug open till it
is merged into Emacs.

Thanks,
andreas