fix handling of http exception (fix ros-infrastructure/buildfarm#152)
fix handling of http exception (fix ros-infrastructure/buildfarm#152)

sorki/rosdep,georgepar/rosdep,wkentaro/rosdep,spaghetti-/rosdep,alessandro-aglietti/rosdep,aymanim/rosdep,aymanim/rosdep,allenh1/rosdep,sorki/rosdep,alessandro-aglietti/rosdep,spaghetti-/rosdep,ros-infrastructure/rosdep,wkentaro/rosdep,georgepar/rosdep,ros-infrastructure/rosdep,allenh1/rosdep