travis ci: attempt to fix python3 run
travis ci: attempt to fix python3 run

benthomasson/stdeb,astraw/stdeb,pombredanne/stdeb,benthomasson/stdeb,sathieu/stdeb,pombredanne/stdeb,sathieu/stdeb,astraw/stdeb,sathieu/stdeb,LeMeteore/stdeb,pombredanne/stdeb,benthomasson/stdeb,LeMeteore/stdeb,astraw/stdeb,LeMeteore/stdeb