[pygobject] overrides: Provide _overrides_module attribute to make gst-python overrides work again.

[Christoph Reiter <creiter src gnome org>]

commit 64be2069d39b4d2767eb1efd47bb3f268ad7fb0d
Author: Christoph Reiter <creiter src gnome org>
Date:   Thu Apr 23 22:03:54 2015 +0200

    overrides: Provide _overrides_module attribute to make gst-python overrides work again.
    
    gi_gst_fraction_from_value () in gst-python's gstmodule.c tries to access
    the Gst.Fraction class through gi.repository.Gst._overrides_module.Fraction
    and failed since _overrides_module was removed in revision 149c31beced944c.
    
    This adds it back pointing to the proxy itself which also contains Gst.Fraction.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=736678#c6

 gi/overrides/__init__.py |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/gi/overrides/__init__.py b/gi/overrides/__init__.py
index 62cfd30..bc915b2 100644
--- a/gi/overrides/__init__.py
+++ b/gi/overrides/__init__.py
@@ -117,6 +117,13 @@ def load_overrides(introspection_module):
         if has_old:
             sys.modules[module_key] = old_module
 
+    # backwards compat: for gst-python/gstmodule.c,
+    # which tries to access Gst.Fraction through
+    # Gst._overrides_module.Fraction. We assign the proxy instead as that
+    # contains all overridden classes like Fraction during import anyway and
+    # there is no need to keep the real override module alive.
+    proxy._overrides_module = proxy
+
     override_all = []
     if hasattr(override_mod, "__all__"):
         override_all = override_mod.__all__