coloring by an attribute with all zeroes except one gives infinite wait

[terraswat]

Facts:

• all of the attribute values are zero except one
• the attributes are loaded via the UI with 'Add Attributes'
• 151 nodes
• map: https://tumormap.ucsc.edu/?p=chrisw_soe.ucsc.edu/ktb_151_samples_5000_hugo_20190326

Symptoms:

• get an infinite wait when coloring by this attribute
• the legend shows as range
• the shortlist shows as two categories
• it may only happen when all of the values are zero except one

on