have entities resolve relative to xml files defining them

I had broken out parts of my maven.xml file to entities. My structure basically looks like this:

superproj/

In maven.xml, there's a section that looks like:

<!DOCTYPE Project [
<!ENTITY build SYSTEM "buildconf/maven-test.xml">
]>

The problem is, when I go into subproj (whose project.xml inherits from superproj's project.xml) and run a maven command, maven tries to resolve the entity to subproj/buildconf/maven-test.xml.

That's why I'd like it to be relative to maven.xml.

I will attach a patch.