Make spec_for_() calls explicit

_distutils_hack/__init__.py

@@ -82,11 +82,14 @@ def match(self, string):
 class DistutilsMetaFinder:
     def find_spec(self, fullname, path, target=None):
         if path is not None:
-            return
-
-        method_name = 'spec_for_{fullname}'.format(**locals())
-        method = getattr(self, method_name, lambda: None)
-        return method()
+            return None
+
+        if fullname == "distutils":
+            return self.spec_for_distutils()
+        elif fullname == "pip":
+            return self.spec_for_pip()
+        else:
+            return None
 
     def spec_for_distutils(self):
         import importlib