why do you need to delete bzrlib when installing

[Martin Pool]

If I do

  python setup.py install --home ~

it ought to overwrite ~/lib/python/bzrlib, but it does not seem to do
so.  I have seen John tell people they need to remove that directory
first.  I thought this used to work... does anyone know what has
changed in our setup.py or in Python so that it doesn't work anymore?

Maybe we should add an instruction to the install documentation?

-- 
Martin