demmt: do not print "subchannel already taken" messages when buffer is known-invalid
demmt: do not print "subchannel already taken" messages when buffer is known-invalid

pierremoreau/envytools,grate-driver/envytools,pierremoreau/envytools,MoochMcGee/envytools,hakzsam/envytools,karolherbst/envytools,kfractal/envytools,kfractal/envytools,grate-driver/envytools,MoochMcGee/envytools,hakzsam/envytools,kfractal/envytools,hakzsam/envytools,MoochMcGee/envytools,hakzsam/envytools,MoochMcGee/envytools,pierremoreau/envytools,envytools/envytools,envytools/envytools,grate-driver/envytools,kfractal/envytools,karolherbst/envytools,envytools/envytools,envytools/envytools,karolherbst/envytools,kfractal/envytools,MoochMcGee/envytools,karolherbst/envytools,grate-driver/envytools,karolherbst/envytools,envytools/envytools,pierremoreau/envytools,hakzsam/envytools,grate-driver/envytools,pierremoreau/envytools