Recently I've added this test named test_ttk_guionly, and I noticed some
buildslaves went red, like amd64 gentoo trunk and x86 FreeBSD trunk (I
though there were others for the reason I'm going to say next, but
didn't found on a quick look).

amd 64 gentoo trunk is failing with:

.
.
test_ttk_guionly
test_ttk_guionly skipped -- ttk not available: no display name and no
$DISPLAY environment variable
.
.
test_tcl

remoteFailed: [Failure instance: Traceback (failure with no frames):
twisted.internet.error.ConnectionLost: Connection to the other side was
lost in a non-clean fashion.
]


When it is not test_tcl, it is test_ttk_guionly.
I tried duplicating the issue here by creating a buildmaster and a
buildslave, used same options to build and to run tests, also tried
enabling and disabling pty (I've found some old emails about problems
involving pty), but couldn't duplicate it.

So I followed a build on this buildslave "amd 64 gentoo trunk" and
noticed it took a long time from the time it started running test_tcl
till when the error appeared, which makes me imagine there is some
problem regarding X server authorization. Now this is when I started
checking how many other slaves were failing with the same error, and
then I found this "x86 FreeBSD trunk" which failed with the following
message:

.
.
test_ttk_guionly
test_ttk_guionly skipped -- ttk not available: can't find package tile
.
.
test_tcl
XIO:  fatal IO error 9 (Bad file descriptor) on X server ":0.0"

      after 25 requests (23 known processed) with 1 events remaining.

*** Error code 1

This second bot had DISPLAY set, while the first didn't (although its
TERM is set to xterm). I wonder if the first error ends up being the
same as this second one.

I'm asking myself if test_ttk_guionly is so wrong that it should be
disabled everywhere, and even if it gets disabled, what if in the future
another test comes in and "conflicts" with test_tcl ?