Has BIRT report beahviour changed in RTC 6.0.3 compared to 5.0.2

I have a BIRT report that worked fine in RTC 5.0.2, but after an upgrade to 6.0.3, the behaviour has changed.

The report has an outer loop (as a scripted dataset) and an inner loop (also a scripted dataset). The fetch operations used to be all called before the inner loop started (which was an unexpected behaviour when I first encountered it) but now the inner loop is executed after the first fetch.

I can supply a small report to demonstrate this, but can't see how to attach the file!