The invocation of "xauth list <display>" in client_x11_get_proto() in clientloop.c has a bogus trailing "." argument which causes xauth to unnecessarily try to lookup a display called "." after reporting about the display that we actually care about. Fix is to change the: snprintf(cmd, sizeof(cmd), "%s %s%s list %s . 2>" _PATH_DEVNULL, to: snprintf(cmd, sizeof(cmd), "%s %s%s list %s 2>" _PATH_DEVNULL, Sorry I don't have the actual line number or a real patch but visual inspection should spot this fairly easily.
This has now been fixed in -HEAD and the 4.2 branch and will be in the next release. Thanks for the report.
Change all RESOLVED bug to CLOSED with the exception of the ones fixed post-4.4.