If you have Business::ISBN 2.x installed and you try to install URI, you'll probably get stopped at the `make test` stage. Some of the method names changed to support ISBN-13, but URI up to 1.35 hasn't caught up yet. Unless you're using the obscure ISBN scheme in URLs, you don't really care that it breaks save that it doesn't install nicely. You can force install URI and be just fine (or install it without Business::ISBN already installed).
I've posted the patch for URI to RT so URI can work with either major version of Business::ISBN back to Perl 5.004. It renames a couple of methods in URI::urn::isbn, but still works with the older names (with a warning) too.