Adjusted the test so that it also works when you're testing with an older...

Adjusted the test so that it also works when you're testing with an older setuptools version and there's a new one on pypi.
In that case, the _call_easy_install call will really try to install setuptools first and execute other code paths than the test cares for.
A cleaner way does not seem possible as the easy_install code is really intertwined.

src/zc/buildout/upgrading_distribute.txt

@@ -4,7 +4,7 @@ Installing setuptools/distribute
 Some initial test setup:
 
     >>> import sys
-    >>> import zc.buildout.easy_install
+    >>> import zc.buildout
     >>> dest = tmpdir('sample-install')
 
 Setuptools (0.6something) is packaged as an ``.egg``.  So when installing it,
@@ -28,6 +28,21 @@ be printed.  We call ``_call_easy_install()`` directly and get an error
 because of a non-existing tarball, but that's the OK for this corner case
 test: we only want to test that ``_get_dist()`` isn't getting called:
 
+    >>> class MockDist(object):
+    ...     def __str__(self):
+    ...         return 'nonexisting.tgz'
+    ...     @property
+    ...     def project_name(self):
+    ...         # Testing corner case: there *is* actually
+    ...         # a newer setuptools package on pypi than we
+    ...         # are running with, so it really installs it
+    ...         # and compares project_name. We're past the
+    ...         # point that we're testing, so we just raise
+    ...         # the normally expected error.
+    ...         raise zc.buildout.UserError(
+    ...             "Couldn't install: nonexisting.tgz")
+    >>> dist = MockDist()
+
     >>> installer = zc.buildout.easy_install.Installer(
     ...     dest=dest,
     ...     links=[link_server],
@@ -35,8 +50,7 @@ test: we only want to test that ``_get_dist()`` isn't getting called:
     ...     executable=sys.executable,
     ...     always_unzip=True)
     >>> installer._get_dist = mock_get_dist
-    >>> installer._call_easy_install('setuptools', None, dest, 
-    ...                              'nonexisting.tgz')
+    >>> installer._call_easy_install('setuptools', None, dest, dist)
     Traceback (most recent call last):
     ...
     UserError: Couldn't install: nonexisting.tgz