Try to fix Travis, cont.

23Skidoo · 23Skidoo · commit 91911e8d425e · 2018-11-12T08:35:45.000Z
diff --git a/cabal.project.travis.libonly b/cabal.project.travis.libonly
@@ -2,7 +2,7 @@
 -- field. Needed for LIB_ONLY configurations that can't build cabal-install,
 -- only lib:Cabal.
 
-packages: Cabal/
+packages: Cabal/ cabal-testsuite/
 constraints: unix >= 2.7.1.0
 
 -- Uncomment to allow picking up extra local unpacked deps:
