Per email thread on devel list:

Revert "OPAL: drop dead with core on bad flow. rarely happens with helloworld on large scale."

This reverts commit 86f1d5af3ee484f34092ad3f7a645d9a5ccbcb6c.

Will be reconsidered via RFC as it represents a significant change in behavior

opal/class/opal_list.h

@@ -486,7 +486,6 @@ static inline opal_list_item_t *opal_list_remove_item
     if (!found) {
         fprintf(stderr," Warning :: opal_list_remove_item - the item %p is not on the list %p \n",(void*) item, (void*) list);
         fflush(stderr);
-        abort();
         return (opal_list_item_t *)NULL;
     }