This cropped up in #4952, where we marked it as `skip` (https://github.com/pymc-devs/pymc3/pull/4952/commits/6249cf5082e7adb9c62ac78debb1cc20b8de5d9d) because it passed in one of the runs but failed in the next one. It fails locally for me as well.