python-sphinx creates unreproducible documentation by:

Known affected packages

Detection

Example debbindiff output with memory references and an unsorted index file

Example diff with and without network access:

-<li><strong>to_addr</strong> (<a class="reference external" href="https://docs.python.org/3/library/stdtypes.html#str" title="(in Python v3.6)"><em>str</em></a>) – the email to use as “to” (defaults to
+<li><strong>to_addr</strong> (<em>str</em>) – the email to use as “to” (defaults to

Solution

For unsorted stuff, patch submitted as 776443.

For the external links, see 877895 for the full discussion.

Workaround: use the "multiple target" feature introduced in Sphinx 1.3 in the intersphinx_mapping configuration, like such:

intersphinx_mapping = {
    'python': ('https://docs.python.org/3/',
               ('/usr/share/doc/python3-doc/html/objects.inv', None)),
}

Make sure you add the right build-dep for the docs packages referenced (in the above case, python3-doc.