map.setPaintProperty() fill-color not redrawing after modifying stops

[jhurlb]

mapbox-gl-js version:
0.42.1 & 0.42.2

Steps to Trigger Behavior

1. Create a layer with paint property 'fill-color' and give it a range of stops
2. Modify the stops color and call map.setPaintProperty() with the new stops
3. Observe 1 of 2 outcomes: Either the layer redraws only once and not again, or the layer does not redraw at all.

Expected Behavior

When modifying stops and calling map.setPaintProperty() the layer should redraw with the correct stops colors

Actual Behavior

When modifying stops and calling map.setPaintProperty() the layer redraws only once or not at all

Fiddles:
0.42.0 - WORKS
https://jsfiddle.net/bmdqb0nv

0.42.1 - BROKEN
https://jsfiddle.net/9qj1szd6

0.42.2 - BROKEN
https://jsfiddle.net/a7qo64s2

Workaround

call map.setPaintProperty(<layer name>, 'fill-color'); before using the new stops.

[mollymerp]

thanks for the thorough report @justinhurlburt. this bisects to 7e87d7c

[mollymerp]

this line 7e87d7c#diff-0fcf9ef37a1614185cad0dcbd5ec5529L775 is always returning true in the current code, so _updateLayer is never called. it seems the style is already updated before layer.setPaintProperty is called 💭
cc @jfirebaugh

[jfirebaugh]

As a workaround, avoid updating fillColor.stops in place -- generate a fresh array for each setPaintProperty call.