Build with an invalid Git submodule

This build should fail because it has an invalid git submodule: invalid.

head: cannot open '../submodule/README.rst' for reading: No such file or directory

Sphinx configuration file used to build this docs (see full file),

 1# -*- coding: utf-8 -*-
 2
 3# Default settings
 4project = 'Test Builds'
 5extensions = [
 6    'sphinx_autorun',
 7]
 8
 9latex_engine = 'xelatex'  # allow us to build Unicode chars
10
11
12# Include all your settings here
13html_theme = 'sphinx_rtd_theme'
14
15
16
17

>>> # Build at
>>> import datetime
>>> datetime.datetime.utcnow()  # UTC
datetime.datetime(2022, 6, 22, 8, 31, 53, 629996)