Obscure bug when using Zeus hydro - likely does not affect anything. This only came up when running in debug with memory leak detection.
Densfield is left as -1 when AccelerationHack is True in grid::InterpolateBoundaryFromParent. The use of Densfield was not housed by an AccelerationHack != True check in the edited lines. Fixing this.
Is there a possible reason we would want to perpetuate the information about the density field to the acceleration interpolation?
That's probably not particularly germane to this PR, and probably a higher order affect, but if there's an inconsistency between, velocity interpolation and the acceleration interpolation, that could lead to odd glitches that are nearly impossible to find.
This passes the test suite. I'm going to approve and merge.