diff --git a/_pytest/config.py b/_pytest/config.py
index 5abb13d5a..0485d5381 100644
--- a/_pytest/config.py
+++ b/_pytest/config.py
@@ -999,24 +999,29 @@ class Config(object):
         self._warn_about_missing_assertion(mode)
 
     def _mark_plugins_for_rewrite(self, hook):
-                import pkg_resources
-                self.pluginmanager.rewrite_hook = hook
-                for entrypoint in pkg_resources.iter_entry_points('pytest11'):
-                    # 'RECORD' available for plugins installed normally (pip install)
-                    # 'SOURCES.txt' available for plugins installed in dev mode (pip install -e)
-                    # for installed plugins 'SOURCES.txt' returns an empty list, and vice-versa
-                    # so it shouldn't be an issue
-                    for metadata in ('RECORD', 'SOURCES.txt'):
-                        for entry in entrypoint.dist._get_metadata(metadata):
-                            fn = entry.split(',')[0]
-                            is_simple_module = os.sep not in fn and fn.endswith('.py')
-                            is_package = fn.count(os.sep) == 1 and fn.endswith('__init__.py')
-                            if is_simple_module:
-                                module_name, ext = os.path.splitext(fn)
-                                hook.mark_rewrite(module_name)
-                            elif is_package:
-                                package_name = os.path.dirname(fn)
-                                hook.mark_rewrite(package_name)
+        """
+        Given an importhook, mark for rewrite any top-level
+        modules or packages in the distribution package for
+        all pytest plugins.
+        """
+        import pkg_resources
+        self.pluginmanager.rewrite_hook = hook
+        for entrypoint in pkg_resources.iter_entry_points('pytest11'):
+            # 'RECORD' available for plugins installed normally (pip install)
+            # 'SOURCES.txt' available for plugins installed in dev mode (pip install -e)
+            # for installed plugins 'SOURCES.txt' returns an empty list, and vice-versa
+            # so it shouldn't be an issue
+            for metadata in ('RECORD', 'SOURCES.txt'):
+                for entry in entrypoint.dist._get_metadata(metadata):
+                    fn = entry.split(',')[0]
+                    is_simple_module = os.sep not in fn and fn.endswith('.py')
+                    is_package = fn.count(os.sep) == 1 and fn.endswith('__init__.py')
+                    if is_simple_module:
+                        module_name, ext = os.path.splitext(fn)
+                        hook.mark_rewrite(module_name)
+                    elif is_package:
+                        package_name = os.path.dirname(fn)
+                        hook.mark_rewrite(package_name)
 
     def _warn_about_missing_assertion(self, mode):
         try: