It's worth noting that this issue now affects every installation of Debian testing track with systemd and systemd-cron installed; the python program /lib/systemd/system-generators/systemd-crontab-generator is called very early in the boot process; it imports hashlib (although only .md5() is used) and blocks on getrandom(), delaying boot time until a 90s timeout has occurred.

Suggestions: modify hashlib to avoid calling getrandom() until entropy is actually required, rather than on import; change the logic to use /dev/urandom (or an in-process PRNG) when getrandom() blocks; or both.