The following *library* dependencies do not install out of the box on Python 3 using setuptools/pip (with py3 port status in brackets):
- mwlib (switched to mwparserfromhell in T95142)
- oursql ( https://launchpad.net/oursql/py3k/ - requires compiler and mysql headers)
- mysqldb (various; a mess)
- Pywikibot depends on either oursql or mysqldb. switeched to PyMySQL in T89976
- pydot ( https://bitbucket.org/prologic/pydot - only used by interwiki_graph, which is only used by the interwiki script - ported to py3 in v1.2)
- pYsearch (no sign of life at http://pysearch.sourceforge.net/ or https://developer.yahoo.com/python/python-pysearch.html - removed in T106085)
- lunatic-python (no sign of life and all forks currently failing, solved in 2f8c4a3277)
- pywin32 (seems to support py3 since June 2015, solved in 85f3f50ccb86)
- pywinauto (seems to support py3 since April 2018, solved in 85f3f50ccb86)
- flickrapi (seems to support py3 since v2.x, see T102860)
- nosetrim (no sign of life, using @jayvdb's fork)