I also ran the Python test suite on Debian sid using the master branch of Python and all tests pass:
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$ ./configure --prefix=/usr --enable-ipv6 --enable-loadable-sqlite-extensions --with-dbmliborder=bdb:gdbm --with-computed-gotos --without-ensurepip --with-system-expat --with-system-libmpdec  --with-system-ffi
$ make
$ LD_LIBRARY_PATH=$PWD ./python -m test -j0 test_cmd_line_script test_compileall test_importlib test_multiprocessing_main_handling test_py_compile test_runpy

All 6 tests OK.
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I also ran the full test suite on Debian Stretch: again, all tests passed.

Maybe the package builder use a custom configuration or patches? Or issues are specific to Python 3.7? (again, I tested the master branch)