First setuptools, then wheel - not both at once.

tests/test_environment.py

@@ -124,15 +124,16 @@ def bad_interpreter(include_site_extras=True):
 
   interpreter = bad_interpreter(include_site_extras=False)
   with ENV.patch(PEX_VERBOSE='9'):
-    with temporary_dir()as cache:
+    with temporary_dir() as cache:
       # We need to run the bad interpreter with a modern, non-Apple-Extras setuptools in order to
       # successfully install psutil.
-      for dist in resolver.resolve([SETUPTOOLS_REQUIREMENT, WHEEL_REQUIREMENT],
-                                   cache=cache,
-                                   # We can't use wheels since we're bootstrapping them.
-                                   precedence=(SourcePackage, EggPackage),
-                                   interpreter=interpreter):
-        interpreter = interpreter.with_extra(dist.key, dist.version, dist.location)
+      for requirement in (SETUPTOOLS_REQUIREMENT, WHEEL_REQUIREMENT):
+        for dist in resolver.resolve([requirement],
+                                     cache=cache,
+                                     # We can't use wheels since we're bootstrapping them.
+                                     precedence=(SourcePackage, EggPackage),
+                                     interpreter=interpreter):
+          interpreter = interpreter.with_extra(dist.key, dist.version, dist.location)
 
       with nested(yield_pex_builder(installer_impl=WheelInstaller, interpreter=interpreter),
                   temporary_filename()) as (pb, pex_file):