Fix test failures on Python 3.8.0a1 (#15)

* Avoid the deprecated cgi.escape

Fixes test failures on Python 3.8 prereleases (where cgi.escape is not
just deprecated, but gone entirely).

.travis.yml

@@ -1,5 +1,4 @@
 language: python
-sudo: false
 python:
     - 2.7
     - 3.4
@@ -11,7 +10,8 @@ matrix:
     include:
         - python: "3.7"
           dist: xenial
-          sudo: true
+        - python: "3.8-dev"
+          dist: xenial
 install:
     - pip install -U pip setuptools
     - pip install -U coverage coveralls

CHANGES.rst

@@ -5,7 +5,8 @@
 4.4 (unreleased)
 ================
 
-- Nothing changed yet.
+- Fix test failures and deprecation warnings occurring when using Python 3.8a1.
+  (`#15 <https://github.com/zopefoundation/zope.tales/pull/15>`_)
 
 
 4.3 (2018-10-05)

src/zope/tales/tales.py

@@ -18,6 +18,11 @@
 __docformat__ = "reStructuredText"
 import re
 
+try:
+    from html import escape
+except ImportError:
+    from cgi import escape
+
 from zope.interface import implementer
 from zope.interface import Interface
 import six
@@ -822,5 +827,4 @@ def getInfo(self, as_html=0):
         if not as_html:
             return '   - Names:\n      %s' % s.replace('\n', '\n      ')
 
-        from cgi import escape
         return '<b>Names:</b><pre>%s</pre>' % (escape(s))

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    py27,py34,py35,py36,py37,pypy,pypy3,coverage,docs
+    py27,py34,py35,py36,py37,py38,pypy,pypy3,coverage,docs
 
 [testenv]
 commands =