Wikimedia Bugzilla is closed!

For some reason, non-breaking spaces turn into ordinary spaces if there is a
block of preformatted text earlier on the page.  A minimal test case is:

a&nbsp;b<pre>c</pre>d&nbsp;e

The non-breaking space between a and b is rendered correctly, but for some
reason the one between d and e becomes an ordinary space.  A slightly longer
test case, which should illustrate the problem clearly in CSS-capable browsers,
is at the URL given above.