["python","pip"]
pip uses incorrect cached package version, instead of the user-specified version

I need to install psycopg2 v2.4.1 specifically. I accidentally did: pip install psycopg2 Instead of: pip install psycopg2==2.4.1 That installs 2.4.4 instead of the earlier version. Now even after I pip uninstall psycopg2 and attempt to reinstall with the correct version, it appears that pip is re-using the cache it downloaded the first time. How can I force pip to clear out its download cache and use the specific version I'm including in the command?
If using pip 6.0 or newer, try adding the --no-cache-dir option (source). If using pip older than pip 6.0, upgrade it with pip install -U pip.