Comment 4 for bug 1875109

can confirm this is fixed in the proposed version -- thanks!

(venv) root@76a706fdb5e0:/babi# apt update -qq && apt install tmux
7 packages can be upgraded. Run 'apt list --upgradable' to see them.
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
  tmux
1 upgraded, 0 newly installed, 0 to remove and 6 not upgraded.
Need to get 292 kB of archives.
After this operation, 3072 B disk space will be freed.
Get:1 http://archive.ubuntu.com/ubuntu focal-proposed/main amd64 tmux amd64 3.0a-2ubuntu0.1 [292 kB]
Fetched 292 kB in 1s (279 kB/s)
debconf: delaying package configuration, since apt-utils is not installed
(Reading database ... 8572 files and directories currently installed.)
Preparing to unpack .../tmux_3.0a-2ubuntu0.1_amd64.deb ...
Unpacking tmux (3.0a-2ubuntu0.1) over (3.0a-2) ...
Setting up tmux (3.0a-2ubuntu0.1) ...
(venv) root@76a706fdb5e0:/babi# pytest tests -k resize
============================= test session starts ==============================
platform linux -- Python 3.8.2, pytest-5.4.2, py-1.8.1, pluggy-0.13.1
rootdir: /babi
collected 507 items / 484 deselected / 23 selected

tests/features/resize_test.py .......... [ 43%]
tests/features/save_test.py . [ 47%]
tests/features/resize_test.py .......... [ 91%]
tests/features/save_test.py . [ 95%]
tests/features/suspend_test.py . [100%]

====================== 23 passed, 484 deselected in 6.95s ======================