[Moved to DR at the November, 2014 meeting.]

Proposed resolution (June, 2014):

This issue is resolved by the resolution of issue 1351.

It is unspecified if an implicitly-defined copy assignment operator directly invokes the copy assignment operators of virtual bases. The exception-specification of such a copy assignment operator is thus also unspecified. The specification in 14.5 [except.spec] paragraph 14 should explicitly include the exceptions from the copy assignment operators of virtual base classes, regardless of whether the implicit definition actually invokes the virtual base assignment operators or not.