[Python-modules-team] Bug#948733: TypeError: '_traversal_list' object is not reversible

[Helmut Grohne]

Package: python3-sphinx
Version: 1.8.5-4
Severity: serious
File: /usr/lib/python3/dist-packages/sphinx/util/nodes.py
Tags: upstream fixed-upstream ftbfs
Forwarded: https://github.com/sphinx-doc/sphinx/issues/6887
Control: affects -1 + src:cyrus-sasl2

cyrus-sasl2 fails to build from source in unstable. A build ends with:

| /usr/bin/sphinx-build -d docsrc/.doctrees -n -q -b cyrman ./docsrc ./man
| /<<PKGBUILDDIR>>/build-heimdal/docsrc/exts/sphinxlocal/roles/saslman.py:21: RemovedInSphinx20Warning: app.info() is now deprecated. Use sphinx.util.logging instead.
|   app.info('Initializing saslman plugin')
| WARNING: The config value `author' has type `list', defaults to `str'.
| WARNING: The config value `epub_author' has type `str', defaults to `list'.
| WARNING: The config value `epub_publisher' has type `str', defaults to `list'.
| 
| Exception occurred:
|   File "/usr/lib/python3/dist-packages/sphinx/util/nodes.py", line 97, in apply_source_workaround
|     for classifier in reversed(node.parent.traverse(nodes.classifier)):
| TypeError: '_traversal_list' object is not reversible
| The full traceback has been saved in /tmp/sphinx-err-uv4vtt5x.log, if you want to report the issue to the developers.
| Please also report this if it was a user error, so that a better error message can be provided next time.
| A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
| make[4]: *** [Makefile:1160: man/.sphinx-build.stamp] Error 2
| make[4]: Leaving directory '/<<PKGBUILDDIR>>/build-heimdal'
| make[3]: *** [Makefile:686: all-recursive] Error 1
| make[3]: Leaving directory '/<<PKGBUILDDIR>>/build-heimdal'
| make[2]: *** [Makefile:556: all] Error 2
| make[2]: Leaving directory '/<<PKGBUILDDIR>>/build-heimdal'
| dh_auto_build: cd build-heimdal && make -j8 sasldir=/usr/lib/x86_64-linux-gnu/sasl2 returned exit code 2
| make[1]: *** [debian/rules:164: override_dh_auto_build] Error 255
| make[1]: Leaving directory '/<<PKGBUILDDIR>>'
| make: *** [debian/rules:122: build] Error 2
| dpkg-buildpackage: error: debian/rules build subprocess returned exit status 2

I think the issue is already filed upstream as
https://github.com/sphinx-doc/sphinx/issues/6887.

Helmut