Got this one yesterday just once, unreproducibly:

TEST: gapplication... (pid=27433)
  /gapplication/no-dbus:                                               OK
  /gapplication/basic:                                                 
** ERROR **: 
Expected
-----
activated
open file:///a file:///b
cmdline '40 +' '2'
exit status: 0
-----
Got (full)
-----
activated
cmdline '40 +' '2'
open file:///a file:///b
exit status: 0
-----

cleaning up bus with pid 27454
FAIL
GTester: last random seed: R02Sb06f0c87382f7a2bdff137ef3f89b315


And then again today this one, again just once, unreproducibly:


/gapplication/no-dbus: OK
/gapplication/basic: 
** ERROR **: 
Expected
-----
activated
open file:///a file:///b
cmdline '40 +' '2'
exit status: 0
-----
Got (full)
-----
exit status: 0
-----

cleaning up bus with pid 22012


IIRC, both times the machine was under heavy CPU + IO load from another, parallel, build. 

This is glib git master, on F16.