Cloning petsc
Failed to clone petsc branch firedrake.
Traceback (most recent call last):
  File "firedrake-install", line 453, in git_clone
    raise InstallError("Skipping ssh clone because --disable-ssh")
__main__.InstallError: Skipping ssh clone because --disable-ssh
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "firedrake-install", line 1056, in <module>
    packages = clone_dependencies("PyOP2") + packages
  File "firedrake-install", line 493, in clone_dependencies
    deps.append(git_clone(dep.strip()))
  File "firedrake-install", line 460, in git_clone
    check_call(["git", "clone", "-q", git_url(plain_url, "https")])
  File "firedrake-install", line 366, in check_call
    log.debug(subprocess.check_output(arguments, stderr=subprocess.STDOUT, env=env).decode())
  File "/usr/lib/python3.5/subprocess.py", line 626, in check_output
    **kwargs).stdout
  File "/usr/lib/python3.5/subprocess.py", line 708, in run
    output=stdout, stderr=stderr)