Typo in sub_subset that leads to a crash in the isothermal sphere case.

This bug has been there forever. @jregan uncovered it today by running the isothermal sphere case which has a rather deep tree.

Re-assign to me if happy.

Wow, good catch. Thanks!

Reassigned to @pdraper

We must have been very (un)lucky not to ever hit this before.

Status changed to merged

mentioned in commit 36a2a1b7