I realized that by running command "condor_submit -dump" with a submit file where I set getenv to true. Inside the dump i didn't find any variable "GetEnv", but only the Environment variable set with my env.
So I tried in the python code to set ad['Environment'] = <key>="<value" ... getting the error:
terminate called after throwing an instance of 'boost::python::error_already_set'
Now I tried again setting ad['Env'] as you suggested, but the same error happen! What am i doing wrong?