Merge pull request #1217 from crazy-JiangDongHua/bugfix_undo_plan

Bug in plan enqueue logic where plans could be silently not launched for some communicators. Triggered when both are true:
1. Multiple communicators per ncclGroup.
2. Communicators within a group have different plan counts.
2. Intra-process launch barrier disabled.

Author: jbachan

src/group.cc

@@ -142,15 +142,15 @@ static ncclResult_t doLaunches(struct ncclComm* head) {
     }
 
     while (true) { // Iterate rounds of launches for clique.
-      bool moreRounds;
+      bool moreRounds = false;
       comm = cliqueHead;
       do { // Iterate clique members.
         struct ncclComm* next = comm->groupNext;
         if (useBarrier) {
           // Barrier reduction result tells us if this was the final round.
           moreRounds = 0 != ncclCommIntraBarrierOut(comm);
         } else {
-          moreRounds = comm->unlaunchedPlansHead != nullptr;
+          moreRounds |= comm->unlaunchedPlansHead != nullptr;
         }
         if (moreRounds) {
           // Pop next unlaunched kernel