This can easily happen when series of different length are drawn and the RangeSlider is used to restrict the graph to a range where one of the series is empty.
To make it actually compile again.
In mbostock/d3 issue #1016, the scope of the `tick` class on a svg y-axis element changed to include the entire g object (line and text), not just the line. The Rickshaw CSS for `.y_ticks .tick` was created in the early commits, and sets the style to be a 2px width semitransparent stroke. Due to the change in scoping of the style class, the stroke element applies to both the line and the text element, creating a shadow on the y-axis text labels. By changing the scope of the stroke stanza from `.y_ticks .tick` to `.y_ticks .tick line`, the stroke now applies only to the line, and not to the text element, this removing the stroke shadow on the text label.
x/yScale is coming from the configuration dictionary which may be referenced by the Graph creator, or shared with other Graphs. We need to ensure we copy the scale so that our mutations do not change the object given to us.