subversion 1.5 and unexpected format errors with blank info

We use subversion at work, subversion 1.5 specifically. I was working on a project with a lot of externals and ran into the following error:

Unrecognized format for the relative external URL '&#39 .
Boy is that informative. After poking around and doing all sorts of re-organization of the externals I noticed that I had a dupe. Removing the duplicate external solved the problem. Hope that helps.