The property is not yet tested, working on that.
1 patch for repository http://darcs.net/screened:
patch f5d79f24bab01bad038670f17c2e56c2d7a45b49
Author: Ben Franksen <ben.franksen@online.de>
Date: Sat Jun 15 11:20:33 CEST 2019
* document and add property for PrimPatchId invariant