Fix parserTests regression introduced in r17479.

Fix parserTests regression introduced in r17479.

Example of failing test:
----------------------
Running test Magic links: RFC (bug 479)... FAILED!
--- /tmp/mwParser-1109840392-expected   2006-11-08 05:39:04.000000000 +0000
+++ /tmp/mwParser-1109840392-actual     2006-11-08 05:39:04.000000000 +0000
@@ -1,2 +1,2 @@
-<p><a href="http://www.ietf.org/rfc/rfc822.txt" class="external" title="http://www.ietf.org/rfc/rfc822.txt">RFC 822</a>
+<p><a href="http://www.ietf.org/rfc/rfc822.txt" class="external " title="http://www.ietf.org/rfc/rfc822.txt" rel="nofollow">RFC 822</a>
 </p>
----------------------

Also applied to the "BUG 1887: A RFC with a thumbnail" and "RFC code coverage" tests.