OSX Lion Mail.app bug in signatures containing a URL

This is highly reproducable: try adding an image followed by text in a signature in Mail.app. Now select the image and add a url (CMD+K) e.g. to your company website. So far this should look the way you expect. Now click on some other preference, so Mail saves the signature. I have multiple signatures, so I just click any other signature. Click back on the signature you have just created, and notice how all text that came after the image now is underlined.

Why?

There's a bug in the way Mail saves the webarchive file for the signature (~/Library/Mail/V2/MailData/Signatures/<blabla>.webarchive. When you open this file, you will find a bunch of binary bla, followed by invalid (see missing quotes in attributes below) HTML, that will contain your image similar to this:

<a href="http://www.mywebsite.com/">

<SPAN class="Apple-string-attachment"><OBJECT height=53 width=157 type=application/x-apple-msg-attachment data="cid:60AFAD3F-46C3-487C-A274-E1BB2760158B@fritz.box"></OBJECT></SPAN>

Don't ask me why Mail capitalizes just these tags and not any other tags, but the most important bit is that Mail forgets to add the closing tag </a>, so now everything trailing the image is linked too.

I cannot reproduce this in Safari, so apparently Mail and Safari do not share code here. I have tried what happens when copy/paste a valid rendered HTML file with the appropriate signature text from Safari into Mail, but the result is the same.