readthedocs.org: Build timed out for no apparent reason

Details

• Read the Docs project URL: https://readthedocs.org/projects/astropy/
• Build URL (if applicable): https://readthedocs.org/projects/astropy/builds/12279956/ (just one of many, as example)
• Read the Docs username (if applicable): pllim

Expected Result

Build to happen and succeed.

Actual Result

Timed out after about 1500s but we do not even see the sphinx-build command being run. The logs ends at:

# User's Sphinx configurations
language_user = globals().get('language', None)
latex_engine_user = globals().get('latex_engine', None)
latex_elements_user = globals().get('latex_elements', None)

# Remove this once xindy gets installed in Docker image and XINDYOPS
# env variable is supported
# https://github.com/rtfd/readthedocs-docker-images/pull/98
latex_use_xindy = False

chinese = any([
    language_user in ('zh_CN', 'zh_TW'),
    project_language in ('zh_CN', 'zh_TW'),
])

japanese = any([
    language_user == 'ja',
    project_language == 'ja',
])

if chinese:
    latex_engine = latex_engine_user or 'xelatex'

    latex_elements_rtd = {
        'preamble': '\\usepackage[UTF8]{ctex}\n',
    }
    latex_elements = latex_elements_user or latex_elements_rtd
elif japanese:
    latex_engine = latex_engine_user or 'platex'

# Make sure our build directory is always excluded
exclude_patterns = globals().get('exclude_patterns', [])
exclude_patterns.extend(['_build'])

We are hoping perhaps you can inspect the server log and give us more clue on how to fix this. Thank you very much!

xref astropy/astropy#10998

cc @saimn