Cannot build HTML manual

### Environment - Debian 13.5 (Trixie) - SageMath version 10.9, Release Date: 2026-05-04 Having fetched the 10.9 source and followed this recipe export MAKEFLAGS="-j20" export SAGE_DOC_LANGUAGES="en" make configure ./configure --without-system-python3 make ./sage -i ccache make doc ... and tested, failed, so ... make doc-html ... and tested, failed, so ... ./sage -i sagemath_doc_html ... and tested, failed. ### Steps To Reproduce To replicate the test: From the sage-10.9 source directory, ./sage manual() Result is --------------------------------------------------------------------------- OSError Traceback (most recent call last) Cell In[2], line 1 ----> 1 manual() File sage/misc/lazy_import.pyx:413, in sage.misc.lazy_import.LazyImport.__call__() --> 413 'Could not get source, probably due dynamically evaluated source code.' File ~/src/sage-10.9/src/sage/misc/sagedoc.py:1662, in _sage_doc.reference(self) 1653 def reference(self): 1654 """ 1655 The Sage reference manual. 1656 (...) 1660 sage: manual() # indirect doctest, not tested 1661 """ -> 1662 self._open("reference") File ~/src/sage-10.9/src/sage/misc/sagedoc.py:1635, in _sage_doc._open(self, name, testing) 1633 path = os.path.join(self._base_path, name, "index.html") 1634 if not os.path.exists(path): -> 1635 raise OSError("""The document '{0}' does not exist. Please build it 1636 with 'sage -docbuild {0} html' and try again.""".format(name)) 1638 if testing: 1639 return (url, path) OSError: The document 'reference' does not exist. Please build it with 'sage -docbuild reference html' and try again. Then exit Ignoring the "-docbuild" typo, emit ./sage --docbuild reference html Result is: Error building the documentation. Traceback (most recent call last): File "<frozen runpy>", line 198, in _run_module_as_main File "<frozen runpy>", line 88, in _run_code File "/home/fuzzy/src/sage-10.9/src/sage_docbuild/__main__.py", line 559, in <module> sys.exit(main()) ~~~~^^ File "/home/fuzzy/src/sage-10.9/src/sage_docbuild/__main__.py", line 554, in main build = getattr(builder, typ) AttributeError: 'ReferenceBuilder' object has no attribute 'html' So the documentation appears to be un-buildable or inaccessible from SageMath. ### Config log <!-- Failed to upload "config.log" --> ### Package logs No such file. ### Additional Information _No response_ ### Checklist - [x] I have searched the existing issues for a bug report that matches the one I want to file, without success. - [x] I have read the documentation and troubleshoot guide