[winswitch] xpra-0.17.0 on Centos 7

[Bob Tennent]

 >|This worked for me:
 >|$ yum list xpra | grep "^xpra"
 >|xpra.x86_64                      0.17.0-1.el7_2
 >|@winswitch
 >|$ cat /etc/redhat-release
 >|CentOS Linux release 7.2.1511 (Core)
 >|$ xpra start :10 --start=xterm
 >|(..)
 >|$ xpra attach ssh:localhost:10
 >|(...)
 >|Attached to ssh:localhost:10 (press Control-C to detach)
 >|
 >|Does it work if you run it locally like I did? 

No.  Relevant output:

2016-04-26 02:18:15,944 Connection to the xpra server via SSH failed for: ssh:localhost:10
2016-04-26 02:18:15,945  check your username, hostname, display number, firewall, etc
2016-04-26 02:18:15,945  the command line used was:
2016-04-26 02:18:15,945  ssh -x -T localhost xpra initenv;$XDG_RUNTIME_DIR/xpra/run-xpra _proxy :10 || ~/.xpra/run-xpra _proxy :10 || xpra _proxy :10

 >|Does "xpra list" work?

Yes:

  % xpra list
  Found the following xpra sessions:
  /home/rdt/.xpra:
          LIVE session at :10

Is it relevant that this system uses a non-standard ssh port?

 >|I think I may know what is happening in your case: are
 >|you launching via su from a non-login session?

The xpra server at the remote host is launched using

  su --command="xpra start :100"  rdt

in /etc/rc.d/rc.local.

 >|This would manifest itself as a server start up failure
 >|instead of a client connection failure, but it would fit
 >|the bill.

AFAIK, there's no server start-up failure:

  % xpra list
  Found the following xpra sessions:
  /home/rdt/.xpra:
          LIVE session at :100

xpra 0.16.3 connects to it.

 >|More details on the awful mess created by the XDG_RUNTIME_DIR idea can
 >|be found here:
 >|http://xpra.org/trac/ticket/1129#comment:15

I don't understand this stuff.

 >|If that's the case, you may need to create the directory
 >|"/run/user/$UID" on the server if it does not exist yet,
 >|or edit the config file to not refer to it.

The server is running Centos-6.  It doesn't even have /run.
If "the config file" is /etc/xpra/xpra.conf then the only
reference to /run/user/$UID is

  # bind=/run/user/$UID/xpra/
  bind = ~/.xpra/

which is presumably harmless. 

If I start xpra in a remote session without using su, and try to
connect using 0.17.0, I now get

  XDG_RUNTIME_DIR: Undefined variable.
  2016-04-26 02:43:17,406 The SSH process has terminated with exit code 0
  2016-04-26 02:43:17,407  the command line used was:

as before but nothing more.  

Bob T.