openvswitch: Mishandle of group mods in lib/ofp-util.c:parse_group_prop_ntr_selection_method() allows for assertion failure

An issue was discovered in Open vSwitch OvS, 2.4.x through 2.4.1, 2.5.x through 2.5.5, 2.6.x through 2.6.3, 2.7.x through 2.7.6, 2.8.x through 2.8.4, and2.9.x through 2.9.2, affecting the parsegrouppropntrselectionmethod in lib/ofp-util.c. On controllers with the OpenFlow 1.5 decoder enabled, a...