In random web surfing related to this bug, I noticed the following based on the "homepage" link for this package ( https://github.com/yann2192/pyelliptic/) as shown on the packages page for python-pyelliptic for sid (https://packages.debian.org/sid/python-pyelliptic ).
Specifically, that pyelliptic is (currently) _deprecated_ by its upstream maintainer, specifically _because_ pyelliptic doesn't work with OpenSSL v1.1 and the upstream is unwilling / unable to modify it to work with OpenSSL v1.1. See, for instance, https://github.com/yann2192/pyelliptic/blob/master/README.md (its README file) and https://github.com/yann2192/pyelliptic/issues/50 (Add support OpenSSL 1.1). Given this, I suspect that pyelliptic will never migrate to OpenSSL 1.1 (unless someone desires to fork it and maintain the fork as a "pyelliptic-ng" sort of thing), and that accordingly it will be necessary to remove it from Debian for the Buster release and modify anything depending on it to depend on something else instead. FWIW, I do see that there is a 1.5.8 release of pyelliptic (Debian has 1.5.7-1.1) which removes ECC support, apparently that is something problematic with the < 1.1 version of OpenSSL. I don't know if this would be sufficient to keep pyelliptic in the current Debian Stable release or not. Thanks for your time. Hope this is of some use, interest. Joseph