Error: Bad constraint Products.CMFPlone>=5.0.dev0

I have a Plone 4.3.2 site with and custom packages in src folder. When migrating to Plone 4.3.4, I run into error -- Bad constraint Products.CMFPlone>5.0.dev0.
I guess the issue is from 1.2.7 requirement. After I pin p.a.event to 1.1.4, everything seems working, though I am not sure if this is a good solution.

This is a note for myself and hopefully useful for others.

Might be good to file an issue for this.

I'm getting the same error on a site. is pinned to 1.1 but it still gives the same error. How did you go about identifying the bad package?

from our beloved Mikko: Tracing and fixing Python buildout version conflicts and dependencies.

Maybe it's, where you need to have a version below 1.2 for compatibility with Plone 4.x?

Thanks... @hvelarde and @thet
In my case it was due to a development version of, pulled in by mr.developer (I know I know, production sites shouldn't use mr.developer). The dev version did require Products.CMFPlone>=5.0.dev0. Using a packaged version of pinned to 1.7.1 fixed the issue.

Production sites can use mr.developer; you just have to take care and know what are you doing.