teaser getting loads of <> when creating content from IE6 + Word

Node's teaser generation fails for this kind of contents:

<P style="bla" class="MS-thingy"><SPAN style="hop" class="MS-blabla">Contents</SPAN></P>

(one of my users manages to input this with a combination of (server: Drupal + wysiwyg + TinyMCE) + (client: IE6 + Word))

This gives this teaser:

<><>Contents<><>

This is due to the regex used to filter body when reducing it to a teaser, in modules/node/node.module:

preg_replace('#<([/a-z]*)[^>]*>#', '<\1>', $body);

where [/a-z]* will match nothing because of uppercase HTML tags. Thus the SPAN matches [^>]*, and \1 is the empty string; thus the resulting <>.

First thought about this would be to add uppercase tags to the regex.

However, I prefer forcing everything to lowercase at the start, so that we have a somewhat unified input to rely on (damn IE6, we want you to send us lowercase tags, like everybody else!).

I attach a patch with this solution.