error: cannot open .git/FETCH_HEAD: Permission denied

Traceback (most recent call last):

  File "/Users/master/firedrake/bin/firedrake-update", line 957, in <module>

    git_update("firedrake")

  File "/Users/master/firedrake/bin/firedrake-update", line 381, in git_update

    check_call(["git", "pull"])

  File "/Users/master/firedrake/bin/firedrake-update", line 228, in check_call

    subprocess.check_call(arguments, env=env)

  File "/usr/local/Cellar/python/2.7.10_2/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 540, in check_call

    raise CalledProcessError(retcode, cmd)

subprocess.CalledProcessError: Command '['git', 'pull']' returned non-zero exit status 1