From: Michael Fladischer <FladischerMichael@fladi.at>
Date: Fri, 27 Jan 2017 09:50:38 +0100
Subject: Use local objects.inv where possible

Upstream uses intersphinx mappings that fetch the objects.inv for python by
HTTP from a remote host. Using the local objects.inv from python enables the
package to build without network connection.
---
 docs/conf.py | 37 +++++++++++++++++++++++++++++++------
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/docs/conf.py b/docs/conf.py
index 3c0d080..8095fa0 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 import datetime
 import os
+import sys
 import time
 
 import pkg_resources
@@ -13,12 +14,36 @@ extensions = [
     'sphinx.ext.intersphinx'
     ]
 
-intersphinx_mapping = {
-    'python': ('https://docs.python.org/3/', None),
-    'django': ('https://django.readthedocs.io/en/latest/', None),
-    'pytest': ('https://docs.pytest.org/en/latest/', None),
-    'sybil': ('https://sybil.readthedocs.io/en/latest/', None),
-}
+def check_object_path(key, url, path):
+    if os.path.isfile(path):
+        return {key: (url, path)}
+    return {}
+
+intersphinx_mapping = {}
+intersphinx_mapping.update(check_object_path(
+    'python',
+    'https://docs.python.org/{v}/'.format(
+        v='.'.join(map(str, sys.version_info[0:2]))
+    ),
+    '/usr/share/doc/python{v}/html/objects.inv'.format(
+        v='.'.join(map(str, sys.version_info[0:2]))
+    )
+))
+intersphinx_mapping.update(check_object_path(
+    'django',
+    'https://django.readthedocs.org/en/latest/',
+    '/usr/share/doc/python-django-doc/html/objects.inv'
+))
+intersphinx_mapping.update(check_object_path(
+    'pytest',
+    'https://docs.pytest.org/en/latest/',
+    '/usr/share/doc/python-pytest-doc/html/objects.inv'
+))
+intersphinx_mapping.update(check_object_path(
+    'sybil',
+    'http://sybil.readthedocs.io/en/latest/',
+    '/usr/share/doc/python3-sybil/html/objects.inv'
+))
 
 # General
 source_suffix = '.txt'