[yt-dev] Issue #767: Unitrefactor: Stream datasets are always setting code_length == cm (yt_analysis/yt)

New issue 767: Unitrefactor: Stream datasets are always setting code_length == cm https://bitbucket.org/yt_analysis/yt/issue/767/unitrefactor-stream-datasets-... John ZuHone: I can't get any length units to be returned in anything other than code units: ``` #!python pf = load_uniform_grid(data, ddims, length_unit=2*R*cm_per_kpc) pf.domain_right_edge pf.domain_right_edge.in_units("cm") pf.domain_right_edge.in_units("kpc") ``` gives: ``` #!python YTArray([ 1., 1., 1.]) code_length YTArray([ 1., 1., 1.]) cm YTArray([ 3.24077929e-22, 3.24077929e-22, 3.24077929e-22]) kpc ``` which is what happens regardless of what goes in for `length_unit`. Responsible: MatthewTurk