Update to latest Sphinx for documentation

Roll forward to recent version of sphinx for documentation generation.

Change-Id: I9dadd6304cad15b58d39a1014c6804b4e32363ad

doc/source/transform_github_links.py

@@ -73,7 +73,8 @@ def transform_github_links(app, doctree, fromdocname):
         # Replace the suffix with the correct target format file ending,
         # but only if the link ends with both the correct source suffix
         # and refers to a local file.
-        if link.endswith(source_suffix):
+        for src_suffix in source_suffix:
+            if link.endswith(src_suffix):
                 # absolute paths are considered relative to repo
                 if link.startswith("/"):
                     basepath = ""

test-requirements.txt

@@ -1,7 +1,7 @@
 hacking>=0.11.0,<0.12  # Apache-2.0
 loremipsum
 mock!=1.1.1,<=1.3.0
-Sphinx>=1.1.2,<1.2
+sphinx>=1.5.1  # BSD
 discover
 coverage>=3.6  # Apache-2.0
 fixtures>=0.3.14