Curious Sweep1 bug. Includes example.

Hi all.

I work for a well known international architecture office and use grasshopper everyday. It is fantastic and really helpful.

As most here knows the Sweep1 component can be a bit shaky quite randomly.
Some days ago a found a reproducible case that I would like to share with you and the developers.

In this case the sweep fails when using a polyline rail with line-like and arc-like curves from a corner fillet. Warning: "1. Sweep could not be created".

The mystery: The sweep works if I adjust the length of the end of the rail by moving a control point.

I have made a rhino file and a grasshopper file that should be opened together to illustrate the problem and a screenshot as a reference.

I have solved the problem with the well known rail->polyline workaround but still wanted to give you these files to test with as it seems to be a bug somewhere.
As said I am over it with a workaround but if somebody stumbles upon an explanation I am very curious.

The best regards.
Ejnar Brendsdal.