Buildout 2 should have a clearer warning when run with setuptools

[reinout]

Buildout 2 requires distribute instead of setuptools. The bootstrap guarantees distribute, but we cannot guarantee that the correct bootstrap is being used.

See #81 for how easy it is to miss it and how unclear the error message is: AttributeError: 'NoneType' object has no attribute 'location'.

Would a special try/except like the following be a good idea?

something = pkg_resources.Requirement.parse('distribute')
if something is None:
    if pkg_resources.Requirement.parse('setuptoos') is not None:
        raise WhatAreYouDoingException

[mgedmin]

👍 for clear error messages.

The code itself could look something like

has_distribute = pkg_resources.working_set.find(
        pkg_resources.Requirement.parse('distribute')) is not None
has_setuptools = pkg_resources.working_set.find(
        pkg_resources.Requirement.parse('setuptools')) is not None
if has_setuptools and not has_distribute:
    sys.exit("zc.buildout 2.0.0 needs distribute, not setuptools."
                 "  Are you using an outdated bootstrap.py?  Make sure"
                 " you have the latest version downloaded from"
                 " http://downloads.buildout.org/2/bootstrap.py")

[reinout]

Now I've got to find a way to test this :-)

I get the feeling more and more that it would be handy to add https://pypi.python.org/pypi/mock as a test dependency.

[jaap3]

Yeah that would help greatly... ran into this a couple of times now already.

[reinout]

I copied Marius' code into #84