d3/d3-plugins — pull request #78 by kunalb (2013-09-22 06:05:27+00:00)
Title: [d3-sankey] Throw an error for graphs with cycles

The current behaviour is to go into an infinite loop while trying to
assign depths to nodes in case the graph has cycles. This commit changes
it to explicitly throw an error instead till support for displaying
cycles in sankeys is properly supported.

Tested by modifying http://bost.ocks.org/mike/sankey/ data to have
complex cycles and attempting to render.