Puzzling traceback when python -msphinx.ext.intersphinx is used with an invalid url

[anntzer]

Subject: Puzzling traceback when python -msphinx.ext.intersphinx is used with an invalid url

Problem

When running e.g. python -msphinx.ext.intersphinx https://www.sphinx-doc.org/, one gets a rather puzzling traceback:

Traceback (most recent call last):
  File "/usr/lib/python3.7/site-packages/sphinx/ext/intersphinx.py", line 197, in fetch_inventory
    invdata = InventoryFile.load(f, uri, join)
  File "/usr/lib/python3.7/site-packages/sphinx/util/inventory.py", line 108, in load
    raise ValueError('invalid inventory header: %s' % line)
ValueError: invalid inventory header: 

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/usr/lib/python3.7/site-packages/sphinx/ext/intersphinx.py", line 420, in <module>
    inspect_main(argv=sys.argv[1:])  # type: ignore
  File "/usr/lib/python3.7/site-packages/sphinx/ext/intersphinx.py", line 407, in inspect_main
    invdata = fetch_inventory(MockApp(), '', filename)  # type: ignore
  File "/usr/lib/python3.7/site-packages/sphinx/ext/intersphinx.py", line 199, in fetch_inventory
    raise ValueError('unknown or unsupported inventory version: %r' % exc)
ValueError: ('intersphinx inventory %r not readable due to %s: %s', 'https://www.sphinx-doc.org', 'ValueError', ValueError(...))

Yes, I know that the correct invocation is python -msphinx.ext.intersphinx/objects.inv, but it looks like something went wrong in the formatting of the error reporting (one would expect an error message ending with something like "intersphinx inventory ... not readable due to ..." but not and error while formatting that message...).

Procedure to reproduce the problem

See above.

Error logs / results

See above.

Expected results

See above. Alternatively, it may be worth trying url/objects.inv whenever url fails to be loaded correctly as an intersphinx db (or at least whenever url doesn't end with objects.inv, as I think it is expected that it always has that name?), especially as this is consistent with how the url is specified in conf.py (without the trailing objects.inv).

Reproducible project / your project

N/A

Environment info

• OS: Arch Linux
• Python version: 3.7
• Sphinx version: 1.7.7

[tk0miya]

+1; the error is too ugly.

[tk0miya]

Fixed by #5320.
Thank you for reporting.