Outputs a constraints.txt compatible pinning from a Plone versions.cfg. Requires zc.buildout for parsing the .cfg files, naturally.

make_constraintstxt.py

from pkg_resources import parse_version
from zc.buildout.buildout import Buildout


def get_buildout(version):
    versions_url = 'http://dist.plone.org/release/{version}/versions.cfg'
    url = versions_url.format(version=version)

    buildout = Buildout(
        config_file=url,
        cloptions=[('buildout', 'directory', '/tmp')],
        user_defaults=False,
        )

    return buildout


def get_versions(buildout):
    for version in buildout['versions'].items():
        yield '=='.join(version)

if __name__ == '__main__':
    import sys
    try:
        version = sys.argv[1]
    except:
        version = '5-latest'

    buildout = get_buildout(version)
    print '\n'.join(get_versions(buildout))