Fixed recently-introduced bug in copying 0-length Vectors.
Fixed recently-introduced bug in copying 0-length Vectors.

scamille/simbody,Gjacquenot/simbody,elkingtonmcb/simbody,elkingtonmcb/simbody,scamille/simbody,robojukie/simbody,robojukie/simbody,elen4/simbody,chrisdembia/simbody,elen4/simbody,Gjacquenot/simbody,chrisdembia/simbody,Gjacquenot/simbody,simbody/simbody,robojukie/simbody,simbody/simbody,scamille/simbody,chrisdembia/simbody,elkingtonmcb/simbody