tests: ignore new warning from setuptools 42

setuptools 42.0.0 prints a warning:

   WARNING: The easy_install command is deprecated and will be removed in a future version

use a test normalizer to ignore this warning in doctest.

slapos/recipe/template/tests.py

@@ -26,6 +26,7 @@
 ##############################################################################
 from __future__ import print_function
 import doctest
+import re
 import unittest
 from zc.buildout import testing
 from zope.testing import renormalizing
@@ -37,6 +38,11 @@ def setUp(test):
       run_buildout = lambda: print(system(buildout), end='')
       ))(**test.globs)
 
+
+normalize_setuptools_42 = re.compile(
+    'WARNING: The easy_install command is deprecated and will be removed in a future version\\.\n'), ''
+
+
 def test_suite():
   return unittest.TestSuite([
     doctest.DocFileSuite(
@@ -46,6 +52,7 @@ def test_suite():
       checker=renormalizing.RENormalizing((
         testing.normalize_path,
         testing.not_found,
+        normalize_setuptools_42,
         )),
     ) for filename in [
       'README.txt',