Unable to run makefile


i am using ubuntu 16.04. i am trying to run makefile. but output is;

dep ensure -vendor-only
grouped write of manifest, lock and vendor: error while writing out vendor tree: failed to write dep tree: failed to export …github.com/vmware/govmomi: failed to fetch source for …github.com/vmware/govmomi: unable to get repository: Cloning into ‘/root/go/pkg/dep/sources/https—github.com-vmware-govmomi’…
POST git-upload-pack (gzip 1790 to 945 bytes)
remote: Enumerating objects: 77, done.
remote: Counting objects: 100% (77/77), done.
remote: Compressing objects: 100% (55/55), done.
error: RPC failed; curl 56 GnuTLS recv error (-9): A TLS packet with unexpected length was received.
fatal: The remote end hung up unexpectedly
fatal: early EOF
fatal: index-pack failed
: command failed: [git clone --recursive -v --progress …github.com/vmware/govmomi /root/go/pkg/dep/sources/https—github.com-vmware-govmomi]: exit status 128
Makefile:36: recipe for target ‘deps’ failed
make[1]: *** [deps] Error 1
Makefile:31: recipe for target ‘all’ failed
make: *** [all] Error 2

what is the reason of this?

This looks like a transient network error, I think it will clear up. If it persists then there is some issue communicating with github.com.