New issue 553: _identify_base_chunk for Octree codes should not pre-allocate a mask https://bitbucket.org/yt_analysis/yt/issue/553/_identify_base_chunk-for-octr... Matthew Turk: The mask for child octs should not be allocated during the course of `_identify_base_chunk` if it can at all be avoided. This is costly. Responsible: MatthewTurk