tox: Fixes for smoke environment.

tox.ini

@@ -113,11 +113,14 @@ commands =
     {envpython} scripts/asciidoc2html.py {posargs}
 
 [testenv:smoke]
+passenv = DISPLAY XAUTHORITY HOME
 deps =
     -rrequirements.txt
+# We don't use {[testenv:mkvenv]commands} here because that seems to be broken
+# on Ubuntu Trusty.
 commands =
-    {[testenv:mkvenv]commands}
-    {envpython} -m qutebrowser --debug --no-err-windows --nowindow --temp-basedir about:blank ":later 500 quit"
+    {envpython} scripts/link_pyqt.py --tox {envdir}
+    {envpython} -m qutebrowser --no-err-windows --nowindow --temp-basedir about:blank ":later 500 quit"
 
 [pytest]
 norecursedirs = .tox .venv