Comment 5 for bug 1859610

> Do you have the new python3.7 installed from focal-proposed?

> note, i was running everything from proposed. Since libffi6 & 7 might
> be used by python3.7.

Ah, no I didn't. However, doesn't seem like it makes much difference:

ubuntu@ubuntu:~$ sudo apt install -t focal-proposed python3.7
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
  libpython3.7 libpython3.7-dbg libpython3.7-minimal libpython3.7-stdlib python3.7-dbg python3.7-minimal
Suggested packages:
  python3.7-venv python3.7-doc python3-gdbm-dbg python3-tk-dbg binfmt-support
The following packages will be upgraded:
  libpython3.7 libpython3.7-dbg libpython3.7-minimal libpython3.7-stdlib python3.7 python3.7-dbg
  python3.7-minimal
7 upgraded, 0 newly installed, 0 to remove and 72 not upgraded.
Need to get 32.9 MB of archives.
After this operation, 26.6 kB of additional disk space will be used.
Do you want to continue? [Y/n]
Get:1 http://ports.ubuntu.com/ubuntu-ports focal-proposed/main arm64 python3.7-dbg arm64 3.7.6-1ubuntu2 [15.9 MB]
Get:2 http://ports.ubuntu.com/ubuntu-ports focal-proposed/main arm64 python3.7 arm64 3.7.6-1ubuntu2 [304 kB]
Get:3 http://ports.ubuntu.com/ubuntu-ports focal-proposed/main arm64 libpython3.7 arm64 3.7.6-1ubuntu2 [1373 kB]
Get:4 http://ports.ubuntu.com/ubuntu-ports focal-proposed/main arm64 libpython3.7-dbg arm64 3.7.6-1ubuntu2 [11.4 MB]
Get:5 http://ports.ubuntu.com/ubuntu-ports focal-proposed/main arm64 libpython3.7-stdlib arm64 3.7.6-1ubuntu2 [1717 kB]
Get:6 http://ports.ubuntu.com/ubuntu-ports focal-proposed/main arm64 python3.7-minimal arm64 3.7.6-1ubuntu2 [1723 kB]
Get:7 http://ports.ubuntu.com/ubuntu-ports focal-proposed/main arm64 libpython3.7-minimal arm64 3.7.6-1ubuntu2 [547 kB]
Fetched 32.9 MB in 25s (1316 kB/s)
(Reading database ... 80531 files and directories currently installed.)
Preparing to unpack .../0-python3.7-dbg_3.7.6-1ubuntu2_arm64.deb ...
Unpacking python3.7-dbg (3.7.6-1ubuntu2) over (3.7.6-1) ...
Preparing to unpack .../1-python3.7_3.7.6-1ubuntu2_arm64.deb ...
Unpacking python3.7 (3.7.6-1ubuntu2) over (3.7.6-1) ...
Preparing to unpack .../2-libpython3.7_3.7.6-1ubuntu2_arm64.deb ...
Unpacking libpython3.7:arm64 (3.7.6-1ubuntu2) over (3.7.6-1) ...
Preparing to unpack .../3-libpython3.7-dbg_3.7.6-1ubuntu2_arm64.deb ...
Unpacking libpython3.7-dbg:arm64 (3.7.6-1ubuntu2) over (3.7.6-1) ...
Preparing to unpack .../4-libpython3.7-stdlib_3.7.6-1ubuntu2_arm64.deb ...
Unpacking libpython3.7-stdlib:arm64 (3.7.6-1ubuntu2) over (3.7.6-1) ...
Preparing to unpack .../5-python3.7-minimal_3.7.6-1ubuntu2_arm64.deb ...
Unpacking python3.7-minimal (3.7.6-1ubuntu2) over (3.7.6-1) ...
Preparing to unpack .../6-libpython3.7-minimal_3.7.6-1ubuntu2_arm64.deb ...
Unpacking libpython3.7-minimal:arm64 (3.7.6-1ubuntu2) over (3.7.6-1) ...
Setting up libpython3.7-minimal:arm64 (3.7.6-1ubuntu2) ...
Setting up python3.7-minimal (3.7.6-1ubuntu2) ...
Setting up libpython3.7-stdlib:arm64 (3.7.6-1ubuntu2) ...
Setting up libpython3.7:arm64 (3.7.6-1ubuntu2) ...
Setting up libpython3.7-dbg:arm64 (3.7.6-1ubuntu2) ...
Setting up python3.7 (3.7.6-1ubuntu2) ...
Setting up python3.7-dbg (3.7.6-1ubuntu2) ...
Processing triggers for libc-bin (2.30-0ubuntu3) ...
Processing triggers for man-db (2.9.0-2) ...
Processing triggers for mime-support (3.64ubuntu1) ...
ubuntu@ubuntu:~$ python3 -c "import goocalendar; print(goocalendar.__version__)"
Segmentation fault (core dumped)

I'll keep the SD card around for a few days if you want me to dig into this any further.