fix custom glyphs lookup
fix custom glyphs lookup

ivant/Bokeh.jl,spencerlyon2/Bokeh.jl,ivant/Bokeh.jl,spencerlyon2/Bokeh.jl,bokeh/Bokeh.jl,Laeeth/dbokeh,Laeeth/dbokeh,bokeh/Bokeh.jl,JuliaPackageMirrors/Bokeh.jl,JuliaPackageMirrors/Bokeh.jl