peer channel fetch command is not working as expected when TLS is enabled

 peer channel fetch --help
 Fetch a specified block, writing it to a file.

 Usage:
   peer channel fetch <newest|oldest|config|(number)> [outputfile] [flags]

 Flags:
   -c, --channelID string   In case of a newChain command, the channel ID to create.

peer channel fetch 0 genesis_block.pb -o orderer.example.com:7050 -c "mychannel" --tls $CORE_PEER_TLS_ENABLED --cafile $ORDERER_CA
2017-10-30 21:18:55.304 UTC [msp] GetLocalMSP -> DEBU 001 Returning existing local MSP
2017-10-30 21:18:55.304 UTC [msp] GetDefaultSigningIdentity -> DEBU 002 Obtaining default signing identity
2017-10-30 21:18:55.307 UTC [channelCmd] InitCmdFactory -> INFO 003 Endorser and orderer connections initialized
Error: trailing args detected
Usage:
  peer channel fetch <newest|oldest|config|(number)> [outputfile] [flags]

Flags:
  -c, --channelID string   In case of a newChain command, the channel ID to create.

Global Flags:
      --cafile string                       Path to file containing PEM-encoded trusted certificate(s) for the ordering endpoint
      --logging-level string                Default logging level and overrides, see core.yaml for full syntax
  -o, --orderer string                      Ordering service endpoint
      --ordererTLSHostnameOverride string   The hostname override to use when validating the TLS connection to the orderer.
      --test.coverprofile string            Done (default "coverage.cov")
      --tls                                 Use TLS when communicating with the orderer endpoint
  -v, --version                             Display current version of fabric peer server

peer channel fetch 0 -o orderer.example.com:7050 -c "mychannel" --tls $CORE_PEER_TLS_ENABLED --cafile $ORDERER_CA

peer channel fetch 0 genesis_block.pb -o orderer.example.com:7050 -c "mychannel" --tls --cafile $ORDERER_CA