Within SetLevelTimeStep, a loop over grid calculates the conduction timestep for each grid. The results from the previous timestep calculation are never stored and are thus lost. This fix introduces a temporary variable and a call to min() to ensure that the minimum conduction timestep across grids is found.
nice catch, @dachrist . Nominally it's bad form to approve one's own pull request, but this is a small and simple change. I'll approve and merge.
Ha! I was wondering why it gave me the option to approve my own pull request, and I pressed it out of curiosity. :-)