Bug in %B summary format?

[Mike Woolley <mike@ariel.co.uk>]

Hi There,

I'm using the %B summary line format and occasionally, the root of
the thread is missing the "> ". I haven't noticed any particular
pattern to this, but it does happen quite regularly. The problem also
persists between leaving and re-entering the group.

Here's an example from gnu.emacs.gnus today:

    17-Mar-03 19:56   1k   [Russ Allbery        ]  Re: pipermail archives?
 .  17-Mar-03 20:50   1k   [Paul Moore          ]  Re: Displaying HTML mai
 .  17-Mar-03 20:43   1k   `-> <Paul Moore          >  
 .  17-Mar-03 20:49   3k   [Peter Davis         ]  Re: Merging many differ
 .  17-Mar-03 23:06   1k   `-> <Johan Bockgård      >  
 .+ 17-Mar-03 23:17   2k     `-> [Lars Magne Ingebrigt]  
 .  18-Mar-03 08:32   1k       `-> <Nicolas Kowalski    >  
    18-Mar-03 03:50   1k   [Jesper Harder       ]  Re: problems with posti

Removing the customisations I've made to `gnus-summary-line-format'
(but keeping the %B"), `gnus-sum-thread-tree-single-indent' and
`gnus-sum-thread-tree-single-leaf' make no difference and the problem
still occurs.

Am I missing some other setting (wouldn't be the first time!) or is
this a bug in %B?

Cheers,
Mike