c.f. Issue 1085283. Python's binascii module wouldn't correctly encode binary data to MIME Quoted-Printable format. Python's quopri module depends on binascii's implementation of Quoted-Printable.
It took two years to fix the two of the buglets, but they still refuse to fix the other: correctly encoding octet 0.
Python is supposed to be a high-level language, but their use of C has led to yet another stupid bug and they refuse to fix it. This is frustrating. I'm going to have to copy-and-paste the backup Python implementation of Quoted-Printable out of quopri just to do the right thing.