Not necessarily sensible, or desirable, but quite handy: say, a PostgreSQL client written entirely in Python. So I could include it in PyCS, or require it as a pre-requisite, without making everyone using PyCS download and compile Postgres when they probably have it already installed.
Either that or I should make PyCS install like every other Python project, i.e. using
setup.py, so people with decent package managers (i.e. Debian users) can use the OS-provided Postgres and client, and everyone else can compile from source, i.e. what they'd have to do anyway.