plone/plone.app.layout — pull request #23 by gweis (2013-08-21 02:53:31+00:00)
Title: use conditional import to detect presence of dexterity related item behavior

Checking for successful import should be enough. Looking up the distribution is just an additional source for possible typos. (like in this case where the actual distribution name is plone.app.relationfield).

cheers,