diff -r f89ef18f9824 Doc/tools/extensions/pyspecific.py
--- a/Doc/tools/extensions/pyspecific.py	Wed Dec 14 19:48:38 2016 +0200
+++ b/Doc/tools/extensions/pyspecific.py	Wed Dec 14 20:41:52 2016 -0800
@@ -10,7 +10,9 @@
 """
 
 ISSUE_URI = 'https://bugs.python.org/issue%s'
-SOURCE_URI = 'https://hg.python.org/cpython/file/2.7/%s'
+SOURCE_URI = 'https://github.com/python/cpython/blob/%s/%s'
+
+import patchlevel
 
 from docutils import nodes, utils
 
@@ -69,7 +71,11 @@
     has_t, title, target = split_explicit_title(text)
     title = utils.unescape(title)
     target = utils.unescape(target)
-    refnode = nodes.reference(title, title, refuri=SOURCE_URI % target)
+    version, _ = patchlevel.get_version_info()
+    if version == "3.7":
+        version = "master"
+    refnode = nodes.reference(title, title,
+                              refuri=SOURCE_URI % (version, target))
     return [refnode], []