[Rivet] Rivet crash when applying projection

[David Grellscheid]

> To exclude any false alarms, I have bootstrapped completely fresh
> versions of Rivet & dependencies as follows:
> 
>   ./rivet-bootstrap -j 7 --devmode --hepmc-version=2.05.01 --ignore-lcgext --with-boost=/mt/data-grid/fsiegert/sl4/boost --with-gsl=/usr
> 
>   source rivetenv.sh

I'll try this, too.

   David