extensions: tapdance to get reasonable import error formatting
I'm not thrilled with this, but it seems to work.
#require test-repo
$ . "$TESTDIR/helpers-testrepo.sh"
$ cd "$TESTDIR"/..
$ hg files 'set:(**.py)' | sed 's|\\|/|g' | xargs python contrib/check-py3-compat.py
contrib/python-zstandard/setup.py not using absolute_import
contrib/python-zstandard/setup_zstd.py not using absolute_import
contrib/python-zstandard/tests/common.py not using absolute_import
contrib/python-zstandard/tests/test_compressor.py not using absolute_import
contrib/python-zstandard/tests/test_data_structures.py not using absolute_import
contrib/python-zstandard/tests/test_decompressor.py not using absolute_import
contrib/python-zstandard/tests/test_estimate_sizes.py not using absolute_import
contrib/python-zstandard/tests/test_module_attributes.py not using absolute_import
contrib/python-zstandard/tests/test_roundtrip.py not using absolute_import
contrib/python-zstandard/tests/test_train_dictionary.py not using absolute_import
i18n/check-translation.py not using absolute_import
setup.py not using absolute_import
tests/test-demandimport.py not using absolute_import
#if py3exe
$ hg files 'set:(**.py) - grep(pygments)' -X hgext/fsmonitor/pywatchman \
> | sed 's|\\|/|g' | xargs $PYTHON3 contrib/check-py3-compat.py \
> | sed 's/[0-9][0-9]*)$/*)/'
hgext/convert/transport.py: error importing: <ImportError> No module named 'svn.client' (error at transport.py:*)
hgext/fsmonitor/state.py: error importing: <SyntaxError> from __future__ imports must occur at the beginning of the file (__init__.py, line 30) (error at watchmanclient.py:*)
hgext/fsmonitor/watchmanclient.py: error importing: <SyntaxError> from __future__ imports must occur at the beginning of the file (__init__.py, line 30) (error at watchmanclient.py:*)
mercurial/cffi/bdiff.py: error importing: <ImportError> No module named 'mercurial.cffi' (error at check-py3-compat.py:*)
mercurial/cffi/mpatch.py: error importing: <ImportError> No module named 'mercurial.cffi' (error at check-py3-compat.py:*)
mercurial/cffi/osutil.py: error importing: <ImportError> No module named 'mercurial.cffi' (error at check-py3-compat.py:*)
mercurial/scmwindows.py: error importing: <ImportError> No module named 'msvcrt' (error at win32.py:*)
mercurial/win32.py: error importing: <ImportError> No module named 'msvcrt' (error at win32.py:*)
mercurial/windows.py: error importing: <ImportError> No module named 'msvcrt' (error at windows.py:*)
#endif
#if py3exe py3pygments
$ hg files 'set:(**.py) and grep(pygments)' | sed 's|\\|/|g' \
> | xargs $PYTHON3 contrib/check-py3-compat.py \
> | sed 's/[0-9][0-9]*)$/*)/'
#endif