Failure connecting to ap setup with a mode

[Paul Larson]

One of the tests we run for the network manager snap uncovered this problem on uc18 with network-manager 1.10 snap, but I've also been able to reproduce it in the previous snap version, as well as with core20 and with focal.

On a laptop with intel wifi card, we installed a fresh image (see above) and network-manager snap or deb as appropriate. The most straightforward way to run the test we are using, for example with Ubuntu core 18:
$ sudo snap install checkbox --devmode --channel=uc18/stable

After it is installed:
$ cd /snap/checkbox18/current/providers/plainbox-provider-checkbox/bin
$ ./wifi_nmcli_test.py ap wlan0 a

NB: in the above example, replace wlan0 with the correct device if it's something else, and replace uc18 track and checkbox18 directory as appropriate, if you are using uc20 or focal use the uc20 track.

This test uses network-manager to create an ap, then tries to connect to it.

Output with uc18: https://pastebin.canonical.com/p/CBFqj2Mcgr/
Output with focal: https://pastebin.canonical.com/p/4Shm6pWzpM/

This test can also run in bg mode, and works fine with that. So the test itself works, and network-manager seems to be able to create an AP in some mode, but it doesn't seem to work with a