Call copy() only if there is something to copy.
Call copy() only if there is something to copy.

RepeatedField::begin()/end() will return NULL when the content is empty.
Passing these NULL values to std::copy() will result in runtime complains
from some compilers (e.g., vs2010).

Livefyre/protobuf,google/protobuf,google/protobuf,Livefyre/protobuf,google/protobuf,google/protobuf,google/protobuf,Livefyre/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,Livefyre/protobuf,Livefyre/protobuf