151820: Add the distribution directory to sys.path when running
the setup.py script so that the setup.py script can import modules
from the distribution directory.

CHANGES.txt

@@ -33,6 +33,9 @@ Feature Changes
 Bugs Fixed
 ----------
 
+- 151820: Develop failed if the setup.py script imported modules in
+  the distribution directory.
+
 - The setup command wasn't documented.
 
 - The setup command failed if run in a directory without specifying a

src/zc/buildout/easy_install.py

@@ -994,6 +994,7 @@ if _interactive:
         
 runsetup_template = """
 import sys
+sys.path.insert(0, %(setupdir)r)
 sys.path.insert(0, %(setuptools)r)
 import os, setuptools
 

src/zc/buildout/tests.py

@@ -2328,9 +2328,37 @@ We get an error if we specify anything but true or false:
 
     """
 
+def develop_with_modules():
+    """
+Distribution setup scripts can import modules in the distribution directory:
 
+    >>> mkdir('foo')
+    >>> write('foo', 'bar.py',
+    ... '''# empty
+    ... ''')
 
+    >>> write('foo', 'setup.py',
+    ... '''
+    ... import bar
+    ... from setuptools import setup
+    ... setup(name="foo")
+    ... ''')
 
+    >>> write('buildout.cfg',
+    ... '''
+    ... [buildout]
+    ... develop = foo
+    ... parts = 
+    ... ''')
+
+    >>> print system(join('bin', 'buildout')),
+    Develop: '/sample-buildout/foo'
+
+    >>> ls('develop-eggs')
+    -  foo.egg-link
+    -  zc.recipe.egg.egg-link
+
+    """
 
 
 ######################################################################