edelivery fix

erlang

  status "Generating release"
  __sync_remote "
    [ -f ~/.profile ] && source ~/.profile
    set -e
    cd $DELIVER_TO
    if [ \"$RELEASE_CMD\" = \"rebar\" ]; then
      echo \"using rebar to generate release\"
      $REBAR_CMD $RELEASE_CMD_OPTIONS -f generate
    elif [ \"$RELEASE_CMD\" = \"relx\" ]; then
      echo \"using relx to generate release\"
      $RELX_CMD release
    elif [ \"$RELEASE_CMD\" = \"mix\" ]; then
      echo \"using mix to generate release\"
      MIX_ENV=\"$TARGET_MIX_ENV\" LINK_SYS_CONFIG=\"$LINK_SYS_CONFIG\" LINK_VM_ARGS=\"$LINK_VM_ARGS\" APP=\"$APP\" AUTO_VERSION=\"$AUTO_VERSION\" BRANCH=\"$BRANCH\" SKIP_RELUP_MODIFICATIONS=\"$SKIP_RELUP_MODIFICATIONS\" RELUP_MODIFICATION_MODULE=\"$RELUP_MODIFICATION_MODULE\" $MIX_CMD $_set_auto_version release${_force_no_interaction}${_mix_release_verbose_flag}${_app_flag}${_upgrade_flag}
    fi
  "

basically just remove ${_env_flag} from the MIX_ENV=