Skip a build based on command exit code

Use build.jobs.post_checkout to execute a Git command and check if there are changes in the docs/ directory. If there aren’t changes, we return 439 exit code to cancel the build immediately.

---

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

# -*- coding: utf-8 -*-

# Default settings
project = 'Test Builds'
extensions = [
    'sphinx_autorun',
]

latex_engine = 'xelatex'  # allow us to build Unicode chars


# Include all your settings here
html_theme = 'sphinx_rtd_theme'

---

>>> # Build at
>>> import datetime
>>> datetime.datetime.utcnow()  # UTC
datetime.datetime(2022, 11, 14, 14, 39, 28, 255685)