tests: show graph log before and after widening in more cases I'm about to make some changes to which revisions get sent during widening. Some more tests will make it clearer what changes. I've also switched to graph log so we easily notice if the graph shape changes. Differential Revision: https://phab.mercurial-scm.org/D7091

Greg Ward, author of the original bfiles extension
Na'Tosha Bard of Unity Technologies
Fog Creek Software
Special thanks to the University of Toronto and the UCOSP program