Merge remote-tracking branch 'nccl/master' into develop

tools/topo_expl/topo_expl.cpp

@@ -191,6 +191,9 @@ int main(int argc,char* argv[])
     assert(node_model!=0);
     comm[i].topo = node_model->getSystem(i);
     bootstrapAllGather(&comm[i], allGather1Data);
+    // Mark channels as non initialized.
+    for (int c=0; c<MAXCHANNELS; c++) comm[i].channels[c].id = -1;
+    NCCLCHECK(ncclCalloc((uint32_t**)&comm[i].p2pNet, 1));
   }
 
   struct ncclTopoGraph *treeGraph, *ringGraph, *collNetGraph;