test: disable libnetworkcache requirement from buildout, then install it manually.

slapos/recipe/build/tests.py

@@ -16,7 +16,13 @@ BAD_GIT_REPOSITORY = 'http://git.erp5.org/repos/nowhere'
 REVISION = '2566127'
 
 def setUp(test):
+  # XXX side effect. Disable libnetworkcache because buildout testing
+  # infrastructure doesn't support offline install of external egg "forced"
+  # into itself.
+  zc.buildout.buildout.LIBNETWORKCACHE_ENABLED = False
+
   zc.buildout.testing.buildoutSetUp(test)
+  zc.buildout.testing.install('slapos.libnetworkcache', test)
   zc.buildout.testing.install_develop('slapos.recipe.build', test)
 
 class GitCloneNonInformativeTests(unittest.TestCase):