I set up a job to build "https://SystemVerifier.svn.codeplex.com/svn" with a Poll SCM setting of "*/5 * * * *" (every 5 minutes). This repeatedly builds the job, every 5 minutes. I believe it's because of the URL and how Subversion is storing the URL as "https://systemverifier.svn.codeplex.com/svn", i.e. with a lower-case hostname.

URL hostnames are case-insensitive, IIRC, so Hudson (or the plugin doing the check, not sure exactly) ought to respect that.

The Subversion Polling Log says:

Started on 07-Jan-2010 00:05:45
Workspace doesn't contain https://SystemVerifier.svn.codeplex.com/svn. Need a new build
Done. Took 2.8 sec
Changes found

After switching to the lower-case URL, the Subversion Polling Log says:

Started on 07-Jan-2010 00:10:45
https://systemverifier.svn.codeplex.com/svn is at revision 39,263
Done. Took 5.2 sec
No changes

This might affect other SCMs too.