Using Jenkins 1.570 with SVN plugin 2.4. In the Jenkins Configure System page, the option to Validate repository URLs up to the first variable name is checked.

In our job, we allow the user to specify the revision of source to build.

In the job, the svn URL is specified something like:
http://myserver/svn/repository/branches/v1.0@${REVISION_PARAM}

The validation will throw an error:
"repository/branches/v1.0@" doesn't exist in the repository. Perhaps you mean "repository/branches/v1.0"

This is a specification time validation issue only. The plugin functions properly using a URL specified like this.