You're receiving this bug because the package in Summary has produced _FORTIFY_SOURCE related warnings indicating the presence of a sure overflow in a static buffer.
Even though this is not always an indication of a security problem it might even be. So please check this out ASAP.
By the way, _FORTIFY_SOURCE is disabled when you disable optimisation, so don't try finding out the cause using -O0.
Your friendly neighborhood tinderboxer
Created attachment 252189 [details]
Build log (compressed)
I dont see this anymore with grass-6.4.2