[plone.protect] SyntaxError: unqualified exec is not allowed in function '__call__' it contains a nested function with free variables

Anyone seen this particular error with plone.protect under Plone 5.0/5.1?

yes, here:

Pinning plone.protect 3.1.2 solved the issue...so obviously 3.1.3 is somehow rotten and should be fixed or removed.