Rendering bug with canvas, see: https://jsfiddle.net/chromy/ocdnfbmq/29/

Actual output:
https://imgur.com/a/z0ON7IL

Expected output:
Blank or 1px horizontal line.

This came up while trying to fill the area under a line chart.
It's a bit of a pathological edge case where the line chart is zero over most of the length except for a zero length spike - but the output is still unexpected.