system_tests_policy_oversize_basic test_40 sends a barrage of oversize messages to router INT.A. The router closes the connection to the sender but before that can take effect all 10 messages have arrived at the router's input link.
Internally the proton subsystem delivers the first two messages in the context of the same pn_delivery. This causes an indexing error in dispatch that leads to a use-after-free crash while attempting to clean up the qdr_delivery lost by the duplicate index.
The error shows up commonly on rhel8 and occasionally on fedora 29.