Forget a hashed executable location in bash interactive shell
I often run into the case where I'm working inside a Python virtualenv, and I want to run an executable Python program (e.g., bpython). I run it, forgetting that I have not installed it in my virtualenv so it won't do the right thing. Then, I install bpython in my virtualenv, but if I try to run the new version, bash "remembers" the old one and calls it instead.
To be more concrete:
(venv)$ bpython
(whoops, system-level bpython!)
(venv)$ which bpython
/usr/local/bin/bpython
(venv)$ type bpython
bpython is hashed (/usr/local/bin/bpython)
(venv)$ pip install bpython
(venv)$ which bpython
/Users/lorin/.virtualenvs/venv/bin/bpython
(venv)$ type bpython
bpython is hashed (/usr/local/bin/bpython)
How do I tell the bash prompt to "forget" that the location of bpython is `/usr/local/bin/bpython` for that session?