thanks for the report.
I can reproduce the problem with the 6.02 series. On the other hand this unloading issue is fixed starting with the 6.04 series.
I opened a ticket about this issue: sft.its.cern.ch/jira/browse/ROOT-7674
I’ll attach to it the right priority based on your plans to move to 6.04: I think this is the direction Atlas is taking.
We have made significant changes in the unloading and error recovery code. Those changes are substantial are already in v6.04 and 6.06 release. Since this is so much changes, we have decided so far to not port them to v6.02. If you are unable to use v6.04/08 or the upcoming 6.06 (master for now), please let us know why.