bug#12230: 24.2; revert-buffer in an Info buffer should refresh Info-index-nodes

[Eli Zaretskii]

> From: Juri Linkov <juri@jurta.org>
> Cc: 12230@debbugs.gnu.org
> Date: Sun, 19 Aug 2012 01:31:17 +0300
> 
> > The problem is that info.el caches the Index nodes in the alist stored
> > in Info-index-nodes.  It should therefore remove from that alist the
> > association of the Info file whose buffer is reverted.
> 
> Since `Info-revert-find-node' is not the right place to clear
> the cache because the same problem can occur after killing
> the Info buffer and revisiting the same Info manual manually,
> perhaps the right fix would be to check the modtime of the Info file
> in `Info-find-file' and clear the cache for modified files.

That should do the trick, I think.  Thanks.