bug#17281: 24.4.50; emacs hangs in next-line

[Eli Zaretskii]

> From: Stefan Monnier <monnier@IRO.UMontreal.CA>
> Cc: stefan.hahn@s-hahn.de, 17281@debbugs.gnu.org
> Date: Thu, 17 Apr 2014 08:37:45 -0400
> 
> > Stefan (Monnier), this raises a general issue with next-line: is it
> > supposed to work accurately in a buffer that is not the currently
> > selected window's buffer?
> 
> No.

OK, then the fix in line-pixel-height I committed to prevent it from
inflooping should be good enough.  Those who use next-line from a
buffer that is not in the selected window will simply get a value from
a potentially different buffer.