Where can you force pip to install as \"flat\" and not as \"egg\".
For me it seems random. Sometimes it gets installed as egg, sometime as flat.
pip help i
This does not solve the question why I get sometimes zipped eggs, and sometimes not. But it helps.
You can use this in your ~/.distutils.cfg to avoid installation of zipped eggs:
~/.distutils.cfg
[easy_install] zip_ok = False