No rm:boundArtifact in OSLC query results in 6.0.3 and later?

We have a script issuing OSLC commands against DOORS NG. It works fine in 6.0 - 6.0.2, while it stopped working with 6.0.3.

When tracking down the problem we noticed that the result returned by OSLC queries for artifacts (mainly getting all artifacts of a certain type) the result still contains entries both for the base artifact and the artifact usage in modules, but the latter do no longer contain the "rm:boundArtifact" attribute the script is using to distinguish between those.

Is this a bug or has something changed? We can't find any other attribute which would help us to identify the difference.