Interestingly enough, you were right.

My /home folder resides in an NFS share, which seemed to work for factorio until 0.15 came about.

I moved it to a local folder and 0.15 worked out of the box, there were some crashes upon joining several multiplayer games, but I can't really pinpoint, what ...

No there isn't one, i can create and delete it and if i create the.lock file and leave it be, at startup the same error appears, the file gets deleted and the program stops again.
I hope this isn't confusing.
This happens with absolutely fresh installs of factorio, too.

Game works fine on 14.23.

Auto-Updater updates up to 15.19, restarts the game and then:

0.000 Error Util.cpp:62: Couldn't acquire exclusive lock for /home/user/factorio/.lock: Bad file descriptor. Is another instance already running?

------------- Error -------------
Couldn't acquire exclusive ...