Fix TypeError in ext.coverage logging

If there are any missing modules when using the coverage
builder, a TypeError is thrown instead of a warning message
being printed. The warning message needs a %s in the message
to match the list of missing modules provided as a string.

Author: omad

CHANGES.rst

@@ -118,6 +118,8 @@ Bugs fixed
   for objects documented as ``:py:data:`` to be hyperlinked in function signatures.
 * #13858: doctest: doctest blocks are now correctly added to a group defined by the
   configuration variable ``doctest_test_doctest_blocks``.
+* #13885: Coverage builder: Fix TypeError when warning about missing modules.
+  Patch by Damien Ayers.
 
 
 Testing

sphinx/ext/coverage.py

@@ -156,7 +156,7 @@ def _determine_py_coverage_modules(
         logger.warning(
             __(
                 'the following modules are specified in coverage_modules '
-                'but were not documented'
+                'but were not documented: %s'
             ),
             ', '.join(missing_modules),
         )