We store tlclient.conf on tmpfs on igel, meaning it gets reset every reboot. There is permanent storage available, and we're already using it for known_hosts. So we should probably do the same for tlclient.conf.
I can't reproduce this problem on the Igel terminal here.
Still an issue. Tested on an up to date machine here. Comment 1 was likely a misunderstanding. You need to reboot the device, not just restart the ThinLinc client.
This did actually work at some point, as we are supposed to set up a symlink for tlclient.conf to persistent storage. However, it broke in r28208 for bug 4319 as the way we set that up is very fragile. We also want to do bug 5142, which would break the symlink approach anyway. r28208 also broke our setup for known_hosts. Fortunately, the system already sets up such a symlink as part of Igel's own packaging of ThinLinc. Unfortunately, that stopped working in r35928 for bug 7536, when we started doing atomic updates of known_hosts.