Change directory context manager. From http://code.activestate.com/recipes/576620-changedirectory-context-manager/#c2

context_chdir.py

import contextlib
import os

@contextlib.contextmanager
def working_directory(path):
    """
    A context manager which changes the working directory to the given
    path, and then changes it back to its previous value on exit.
    """
    prev_cwd = os.getcwd()
    os.chdir(path)
    yield
    os.chdir(prev_cwd)