Fix test failures introduced in 067acf75

PKG-INFO for setuptools 3.3 has non-ASCII characters.  This causes
two test failures on Python 2, one of them rather unobvious
(testing_bugfix.txt complains about the different number of logging
handlers, of all things).

src/zc/buildout/tests.py

@@ -3204,10 +3204,10 @@ def makeNewRelease(project, ws, dest, version='99.99'):
         zip = zipfile.ZipFile(dest, 'a')
         zip.writestr(
             'EGG-INFO/PKG-INFO',
-            ((zip.read('EGG-INFO/PKG-INFO').decode()
+            ((zip.read('EGG-INFO/PKG-INFO').decode('ISO-8859-1')
               ).replace("Version: %s" % oldver,
                         "Version: %s" % version)
-             ).encode()
+             ).encode('ISO-8859-1')
             )
         zip.close()
     else: