With ipython 4.0.0 and Python 3.5,
Rpush ends in an error.
Tthe unit test is capturing this nicely (kudos to the writer(s) of the rmagic tests - I am currently thinking that we are finding bugs in ipython, or possibly Python 3.5, thanks to them !).
This is a landing point for rpy2 users. The issue is reported and discussed in the ipython issue tracker: https://github.com/ipython/ipython/issues/8941
(@davclark might have more to say since this is the rmagic)