Testing SymPy in a pure Python environment

[Ondrej Certik]

Hi,

since several times already it happened, that we forgot about some
dependecny on something, that is not on a pure Python 2.4
installation, I just commited a simple script bin/test_pure for
testing it, see the documentation inside (probably only works on
Debian and Ubuntu). Basically:

$ sudo cowbuilder --execute test_pure

is enough. So that before each release, I can now easily check it.

Ondrej