There are projects that, for some reason or another, have different naming conventions upstream, either for the path where new releases show up (the "version URL") or the tarball name (the "regex").

e.g. 0install -- the SF project was originally created as zero-install and the old spelling sticks there.

Now that we separate the project name from the distribution package name, overriding the regex is probably a less common need (we could track the upstream name, and map to a different name to the distro package), but there's still a need to be able to override the version URL.

In the current set up with the Upstream Release Monitoring wiki, one could easily do something like 'SF-DEFAULT:zero-install' -- use the SourceForge default but replace the default package name with the one provided. Right now, a user who doesn't know the particular regex would have to select the Sourceforge backend, do a check, have it fail, copy the URL, change to a custom backend and perform the override by hand...

I propose a UI change that add override fields when choosing a project's backend. If filled the override gets passed along to the backend. Thoughts?