This is a light version of bug 4955.
From ThinLinc 4.10.0 (bug 7302) we verify that we can actually switch to the user's home directory. We added these checks to avoid surprises and weird bugs later in the session.
However it turns out that some customers were running ThinLinc fine enough even if the home directory was broken for a while during startup. With this change they now got a ThinLinc that completely refuses to start sessions.
The proper fix is bug 4955, but until that is fixed we should consider allowing these "best effort" sessions as they seemed to have worked well enough in practice. We should probably put a warning in the log though.
We don't have a NFS with Kerberos environment here to test with, so I simply made the home directory inaccessible for a user to test this code path.
Tested by removing the -x bit on the user's homedirectory:
> Openbox-Message: Unable to change to home directory "/local/home/tester": Åtkomst nekas
Works as intended.