[yt-dev] Issue #780: particle unions getting lost in TimeSeries Enzo data (yt_analysis/yt)

New issue 780: particle unions getting lost in TimeSeries Enzo data https://bitbucket.org/yt_analysis/yt/issue/780/particle-unions-getting-lost-... John ZuHone: The particle union "all" is getting lost from pf.particle_types when you access it from a TimeSeries, making it impossible to get certain fields. Example notebook: https://hub.yt-project.org/nb/oduwuj Responsible: MatthewTurk