[pygobject] Don't leak internal RepositoryError on import.

[Christoph Reiter <creiter src gnome org>]

commit 9b821aa0d60857e612cde9dabe9c8f9f9c60214c
Author: Christoph Reiter <creiter src gnome org>
Date:   Sun Oct 4 11:13:37 2015 +0200

    Don't leak internal RepositoryError on import.
    
    In case a dependency of the imported namespace has a version
    conflict with an already loaded version, import would raise
    RepositoryError.
    
    This fixes it to raise an ImportError instead.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=756033

 gi/importer.py |    7 +++++--
 gi/module.py   |    4 ++++
 2 files changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/gi/importer.py b/gi/importer.py
index 2c4fb9c..5060584 100644
--- a/gi/importer.py
+++ b/gi/importer.py
@@ -28,7 +28,7 @@ import importlib
 from contextlib import contextmanager
 
 import gi
-from ._gi import Repository
+from ._gi import Repository, RepositoryError
 from ._gi import PyGIWarning
 from .module import get_introspection_module
 from .overrides import load_overrides
@@ -116,7 +116,10 @@ class DynamicImporter(object):
         else:
             stacklevel = 4
         with _check_require_version(namespace, stacklevel=stacklevel):
-            introspection_module = get_introspection_module(namespace)
+            try:
+                introspection_module = get_introspection_module(namespace)
+            except RepositoryError as e:
+                raise ImportError(e)
             # Import all dependencies first so their init functions
             # (gdk_init, ..) in overrides get called.
             # https://bugzilla.gnome.org/show_bug.cgi?id=656314
diff --git a/gi/module.py b/gi/module.py
index f27d516..fd8f508 100644
--- a/gi/module.py
+++ b/gi/module.py
@@ -117,6 +117,8 @@ class IntrospectionModule(object):
     These members are then cached on this introspection module.
     """
     def __init__(self, namespace, version=None):
+        """Might raise gi._gi.RepositoryError"""
+
         repository.require(namespace, version)
         self._namespace = namespace
         self._version = version
@@ -263,6 +265,8 @@ def get_introspection_module(namespace):
     """
     :Returns:
         An object directly wrapping the gi module without overrides.
+
+    Might raise gi._gi.RepositoryError
     """
     if namespace in _introspection_modules:
         return _introspection_modules[namespace]