-- The previous version would enter into an infinite loop in the case where we have a graph that looks like:
X -> A -> B
Y -> A -> B
So that the incoming vertices of B all have the same sequence. This would cause us to remodel the graph endless by extracting the common sequence A and rebuilding exactly the same graph. Fixed and unit tested
-- Additionally add a max to the number of simplification cycles that are run (100), which will throw an error and write out the graph for future debugging. So the GATK will always error out, rather than just go on forever
-- After 5 rounds of simplification we start keeping a copy of the previous graph, and then check if the current graph is actually different from the previous graph. Equals here means that all vertices have equivalents in both graphs, as do all edges. If the two graphs are equal we stop simplifying. It can be a bit expensive but it only happens when we end up cycling due to the structure of the graph.
-- Added a unittest that goes into an infinite loop (found empirically in running the CEU trio) and confirmed that the new approach aborts out correctly
-- #resolves GSA-924
-- See https://jira.broadinstitute.org/browse/GSA-924 for more details
-- Update MD5s due to change in assembly graph construction
b115e5c582