diff -r 5392be94ea65 Lib/packaging/install.py
--- a/Lib/packaging/install.py	Tue Jun 07 17:58:50 2011 +0200
+++ b/Lib/packaging/install.py	Wed Jun 08 00:26:14 2011 +0200
@@ -13,7 +13,7 @@
 import shutil
 import logging
 import tempfile
-from sysconfig import get_config_var, get_path
+from sysconfig import get_config_var, get_path, is_python_build
 
 from packaging import logger
 from packaging.dist import Distribution
@@ -488,6 +488,13 @@
 
     Returns True on success, False on failure
     """
+    if is_python_build():
+        message = """You are running this from an uninstalled Python.
+This likely implies that you are trying to install a 3rd-party package
+without a working Python installation. That is unsupported."""
+        logger.error(message)
+        return False
+
     logger.info('Checking the installation location...')
     purelib_path = get_path('purelib')
     # trying to write a file there
diff -r 5392be94ea65 Lib/packaging/tests/test_install.py
--- a/Lib/packaging/tests/test_install.py	Tue Jun 07 17:58:50 2011 +0200
+++ b/Lib/packaging/tests/test_install.py	Wed Jun 08 00:26:14 2011 +0200
@@ -1,5 +1,7 @@
 """Tests for the packaging.install module."""
 import os
+import logging
+from sysconfig import is_python_build
 from tempfile import mkstemp
 
 from packaging import install
@@ -356,6 +358,8 @@
         finally:
             install._install_dist = old_install_dist
 
+    @unittest.skipIf(is_python_build(),
+                     'test not relevant for an uninstalled Python')
     def test_install_permission_denied(self):
         # if we don't have the access to the installation
         # path, we should abort immediatly
@@ -371,6 +375,13 @@
             os.chmod(install_path, old_mod)
             install.get_path = old_get_path
 
+    @unittest.skipUnless(is_python_build(),
+                         'test only relevant for an uninstalled Python')
+    def test_install_from_build(self):
+        project = os.path.join(os.path.dirname(__file__), 'package.tgz')
+        self.assertFalse(install.install(project))
+        self.assertEqual(1, len(self.get_logs(logging.ERROR)))
+
 
 def test_suite():
     suite = unittest.TestSuite()