I'm in Mac OS X 10.10, using
Yep, I see this problem too using python3.5 on Mac OS X 10.10.
This seems to be a bug with the python3 interactive shell - it disables echo for your terminal and does not enable it when you exit(). To fix your terminal, run this command at the bash prompt.
Credit goes to this post.
This bug is tracked here: https://trac.macports.org/ticket/48807
The permanent fix is to install the port py35-readline.
sudo port install py35-readline