Difference in py26-compat packages

Hello, can anyone tell me the difference between these two packages: python2-tornado and py26-compat-tornado python2-msgpack and py26-compat-msgpack-python I noticed that py26-compat-salt requires the python2-XXX packages for build but requires py26-compat-XXX packages for runtime. This would require to maintain two packages for each of these cases. Best wishes, Stefan