bug#8657: 24.0.50; Emacs code that seems to use `*-single-char-property-change' incorrectly

[Katsumi Yamaoka]

Chong Yidong wrote:
> Eli Zaretskii <eliz@gnu.org> writes:
>>> The behavior might have changed at some point in time, explaining the
>>> above code.
>>
>> Or maybe the author was confusing next-single-char-property-change
>> with next-single-property-change.
>>
>> In any case, those tests are redundant, because
>> next-single-char-property-change already returns point-max when it
>> finds no change in properties.

> I went ahead and fixed them accordingly.

But in XEmacs next-single-char-property-change will return nil
if no property change is found.  So I've modified the gnus-sum.el
code into:

  (if (featurep 'xemacs)
      (or (next-single-char-property-change end 'invisible)
          (point-max))
    (next-single-char-property-change end 'invisible))