The default tickFormat with a collapsed domain lacks sufficient precision

[mbostock]

Plot.ruleX([5.5]).plot()

We should probably fallback to formatAuto when there is a collapsed domain.

[mbostock]

Really a D3 bug…

d3.scaleLinear().domain([5.5, 5.5]).tickFormat(7.5)(5.5) // "6"

We don’t handle the tick step being zero well.

[Fil]

moved to d3/d3-scale#286