test-check-py3-compat: exclude thirdparty and cffi which are known to fail Otherwise the following errors would be spilled out: mercurial/cffi/bdiff.py: error importing: <ImportError> cannot import name '_bdiff' (error at bdiff.py:*) mercurial/cffi/bdiffbuild.py: error importing: <ModuleNotFoundError> No module named 'cffi' (error at bdiffbuild.py:*) mercurial/cffi/mpatch.py: error importing: <ImportError> cannot import name '_mpatch' (error at mpatch.py:*) mercurial/cffi/mpatchbuild.py: error importing: <ModuleNotFoundError> No module named 'cffi' (error at mpatchbuild.py:*) mercurial/cffi/osutilbuild.py: error importing: <ModuleNotFoundError> No module named 'cffi' (error at osutilbuild.py:*) mercurial/thirdparty/concurrent/futures/_base.py: invalid syntax: invalid syntax (<unknown>, line *) mercurial/thirdparty/concurrent/futures/process.py: error importing: <SyntaxError> invalid syntax (_base.py, line 416) (error at __init__.py:*) mercurial/thirdparty/concurrent/futures/thread.py: error importing: <SyntaxError> invalid syntax (_base.py, line 416) (error at __init__.py:*) mercurial/thirdparty/zope/interface/_flatten.py: error importing: <ImportError> cannot import name 'Declaration' (error at _flatten.py:*) Some of them can be suppressed by building cffi modules for example, but I don't think it's worth keeping these modules covered by the compatibility checker.