make network connect error message readable
make network connect error message readable

Signed-off-by: allencloud <36603fc76d0c5a59db517817381acc1be27b9499@daocloud.io>

vdemeester/libnetwork,abhi/libnetwork,ityangchen/libnetwork,abhi/libnetwork,tmakita/libnetwork,allencloud/libnetwork,fcrisciani/libnetwork,mahak/libnetwork,docker/libnetwork,kolyshkin/libnetwork,abhi/libnetwork,fcrisciani/libnetwork,tmakita/libnetwork,ityangchen/libnetwork,mahak/libnetwork,docker/libnetwork,mbanikazemi/libnetwork,mbanikazemi/libnetwork,WeiZhang555/libnetwork,medallia/libnetwork,WeiZhang555/libnetwork,medallia/libnetwork,allencloud/libnetwork,kolyshkin/libnetwork,vdemeester/libnetwork,mahak/libnetwork,docker/libnetwork,kolyshkin/libnetwork,vdemeester/libnetwork,medallia/libnetwork