I've took different view on the issue. I've downloaded all 0.23 based hadoop distributions that are officially available at hadoop.apache.org - namely 0.23.0, 0.23.1, 2.0.0, 2.0.1. Please note they all are marked as "alpha".
0.23.0 and 0.23.1 are shipping hsqldb version 188.8.131.52. Versions 2.0.0 and 2.0.1 do not contain any hsqldb jars inside, which make sense as
MAPREDUCE-4197 was about adding jars that are requested by examples but not included.
- hadoop 0.20 and 1.x is shipping hsqldb 1.8
- hadoop 2.x is moving hsqldb out
- other components stayed with 1.8 (oozie is quite important component to us as we're having users actively using it)
- we've upgraded to 2.x only because hadoop seemed to be also upgrading
I would personaly incline to revert those two JIRAs. What do you think guys? (I'll not +1 this on Review board and commit it until we will have an agreement)