$ ./configure -C --without-builtin-hashlib-hashes
$ make clean
$ make
...
The following modules found by detect_modules() in setup.py have not
been built, they are *disabled* by configure:
_blake2               _md5                  _sha1              
_sha256               _sha3                 _sha512            
...
$ ./python -c "import _sha1"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ModuleNotFoundError: No module named '_sha1'