Incorrect SCM URL constructed when using parent POM that is not in the parent directory

In our parent pom we have this:

  <properties>
    <scm.module>master-pom</scm.module>
  </properties>
  <scm>
    <connection>scm:cvs:ext:build@server:/srv/cvs/:${scm.module}</connection>
    <developerConnection>scm:cvs:ext:build@server:/srv/cvs/:${scm.module}</developerConnection>
    <url>http://server/fe/browse/UK-CVS-Rsync/${scm.module}</url>
  </scm>

Our child pom (not in the same directory), has this:

  <artifactId>dd-util</artifactId>
  <properties>
    <scm.module>util</scm.module>
  </properties>

Of course, the child pom is overriding the property. Well, it sort of works.
When building the site of the parent pom, we get:

http://server/fe/browse/UK-CVS-Rsync/master-pom

... which is correct. But when building the site for the child pom, we get:

http://server/fe/browse/UK-CVS-Rsync/util/dd-util

I'm quite confused as to why it whould be appending the artifactId of the child project. The property is getting replaced ok, but the the extra bit? This has got to be a bug.

I'm not releasing the project, just building the site.

Any ideas? If this is against the wrong project, can it be moved?