Fabric Python/Django requirements

gistfile1.py

def update_requirements():
    requirements = os.path.join(env.home, 'requirements')
    with prefix('source %s/bin/activate' % env.python_path):
        with cd(requirements):
            cmd=['pip install']
            cmd += ['--requirement %s' % os.path.join(requirements, 'apps.txt')]
            print(cmd)
            run(' '.join(cmd))