This query returns incorrectly returns no results:

$ butler query-datasets /project/hsc/gen3repo/rc2w02_ssw03 bfKernel --collections='*' 

even though this query succeeds:

$ butler query-datasets /project/hsc/gen3repo/rc2w02_ssw03 'bfKernel' --collections=HSC/calib/unbounded

The latter query certainly felt much slower than it should. We should at least profile it.

Something seems to be going wrong with the logic that attempts to query all RUN collections (and only RUN collections) when the collections are unconstrained.