curtin typehints cause fatal syntax errors during xenial maas deployoments

[Francis Ginther]

I'm trying to deploy xenial to a bare metal amd64 host with maas (using the kernel team's maas server). The deployment fails with:

[ 72.755183] cloud-init[3230]: Traceback (most recent call last):
[ 72.755601] cloud-init[3230]: File "/usr/lib/python3.5/runpy.py", line 184, in _run_module_as_main
[ 72.755932] cloud-init[3230]: "__main__", mod_spec)
[ 72.756266] cloud-init[3230]: File "/usr/lib/python3.5/runpy.py", line 85, in _run_code
[ 72.756611] cloud-init[3230]: exec(code, run_globals)
[ 72.756925] cloud-init[3230]: File "/curtin/curtin/commands/main.py", line 212, in <module>
[ 72.757257] cloud-init[3230]: sys.exit(main())
[ 72.757597] cloud-init[3230]: File "/curtin/curtin/commands/main.py", line 135, in main
[ 72.757884] cloud-init[3230]: add_subcmd(subps, subcmd)
[ 72.758189] cloud-init[3230]: File "/curtin/curtin/commands/main.py", line 29, in add_subcmd
[ 72.758481] cloud-init[3230]: __import__(subcmd_full)
[ 72.758761] cloud-init[3230]: File "/curtin/curtin/commands/collect_logs.py", line 29, in <module>
[ 72.759109] cloud-init[3230]: from .install import CONFIG_BUILTIN, SAVE_INSTALL_CONFIG
[ 72.759418] cloud-init[3230]: File "/curtin/curtin/commands/install.py", line 117
[ 72.759737] cloud-init[3230]: target: str
[ 72.760114] cloud-init[3230]: ^
[ 72.760432] cloud-init[3230]: SyntaxError: invalid syntax
[ 72.795247] cloud-init[3230]: Cloud-init v. 21.1-19-gbad84ad4-0ubuntu1~16.04.2 running 'modules:final' at Fri, 19 May 2023 12:54:13 +0000. Up 62.86 seconds.
[ 72.795632] cloud-init[3230]: 2023-05-19 12:54:23,655 - cc_scripts_user.py[WARNING]: Failed to run module scripts-user (scripts in /var/lib/cloud/instance/scripts)
[ 72.804879] cloud-init[3230]: 2023-05-19 12:54:23,665 - util.py[WARNING]: Running module scripts-user (<module 'cloudinit.config.cc_scripts_user' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_scripts_user.py'>) failed

Xenial using using python3 3.5.1-3.

[Francis Ginther (fginther)]

Are there any workarounds for this issue, such as patching / replacing the version of curtin that maas is using for these xenial deployments?