buildout.cfg を次のように編集。 extends = http://dist.plone.org/release/4.1-latest/versions.cfg ↓ http://dist.plone.org/release/4.2-latest/versions.cfg find-links += http://dist.plone.org/release/4.1.6 ↓ http://dist.plone.org/release/4.2.5…