Merge branch 'master' into merge-master-into-features

2 files changed, 5 insertions, 6 deletions

diff --git a/_pytest/assertion/__init__.py b/_pytest/assertion/__init__.py
index 838ebd058..e0fb4284e 100644
--- a/_pytest/assertion/__init__.py
+++ b/_pytest/assertion/__init__.py
@@ -29,7 +29,7 @@ def pytest_namespace():
 
 
 def register_assert_rewrite(*names):
-    """Register a module name to be rewritten on import.
+    """Register one or more module names to be rewritten on import.
 
     This function will make sure that this module or all modules inside
     the package will get their assert statements rewritten.
diff --git a/_pytest/assertion/rewrite.py b/_pytest/assertion/rewrite.py
index 9ad08391c..abf5b491f 100644
--- a/_pytest/assertion/rewrite.py
+++ b/_pytest/assertion/rewrite.py
@@ -186,16 +186,15 @@ class AssertionRewritingHook(object):
         """
         already_imported = set(names).intersection(set(sys.modules))
         if already_imported:
-            for name in names:
+            for name in already_imported:
                 if name not in self._rewritten_names:
-                    self._warn_already_imported(already_imported)
+                    self._warn_already_imported(name)
         self._must_rewrite.update(names)
 
-    def _warn_already_imported(self, names):
+    def _warn_already_imported(self, name):
         self.config.warn(
             'P1',
-            'Modules are already imported so can not be re-written: %s' %
-            ','.join(names))
+            'Module already imported so can not be re-written: %s' % name)
 
     def load_module(self, name):
         # If there is an existing module object named 'fullname' in