make pytest_plugin_registered a historic hook

--HG--
branch : more_plugin

_pytest/hookspec.py

@@ -19,6 +19,11 @@ def pytest_namespace():
     time.
     """
 
+@hookspec_opts(historic=True)
+def pytest_plugin_registered(plugin, manager):
+    """ a new pytest plugin got registered. """
+
+
 @hookspec_opts(historic=True)
 def pytest_addoption(parser):
     """register argparse-style options and ini-style config values.
@@ -259,9 +264,6 @@ def pytest_doctest_prepare_content(content):
 # error handling and internal debugging hooks
 # -------------------------------------------------------------------------
 
-def pytest_plugin_registered(plugin, manager):
-    """ a new pytest plugin got registered. """
-
 def pytest_internalerror(excrepr, excinfo):
     """ called for internal errors. """