Single File Fetching error

FileFetchError

I tried this :
git archive --remote=git@github.com:git/git.git HEAD:/contrib/completion/ git-completion.bash | tar xvf -

And got this error:
Invalid command: 'git-upload-archive 'git/git.git''
  You appear to be using ssh to clone a git:// URL.
  Make sure your core.gitProxy config option and the
  GIT_PROXY_COMMAND environment variable are NOT set.
fatal: The remote end hung up unexpectedly
tar: This does not look like a tar archive
tar: Exiting with failure status due to previous errors