Merge lp:~cjwatson/storm/py36 into lp:storm

[Colin Watson]

Support Python 3.6 and 3.7.

There were a couple of minor problems:

 * SQLObjectMeta needs to skip the new __classcell__ namespace entry added by the changes for PEP 487.

 * datetime.datetime.astimezone now presumes that naive datetime instances represent system local time rather than raising ValueError, which caused a test to fail. Since this presumption seems unlikely to be a good thing for things like web applications to rely on, forbid this case manually for now.

[Kristian Glass (doismellburning)]

review: Approve

=== modified file 'NEWS'
--- NEWS	2019-09-27 19:22:54 +0000
+++ NEWS	2019-09-29 14:16:49 +0000
@@ -5,6 +5,7 @@
 ---------
 
 - Fix incorrect caching of wrapped DB-API exceptions (bug 1845702).
+- Support Python 3.6 and 3.7.
 
 0.21 (2019-09-20)
 =================
 
=== modified file 'storm/sqlobject.py'
--- storm/sqlobject.py	2019-09-17 09:35:10 +0000
+++ storm/sqlobject.py	2019-09-29 14:16:49 +0000
@@ -167,6 +167,8 @@
 
         attr_to_prop = {}
         for attr, prop in list(six.iteritems(dict)):
+            if attr == "__classcell__":  # Python >= 3.6
+                continue
             attr_to_prop[attr] = attr
             if isinstance(prop, ForeignKey):
                 db_name = prop.kwargs.get("dbName", attr)
 
=== modified file 'storm/variables.py'
--- storm/variables.py	2019-08-11 16:57:24 +0000
+++ storm/variables.py	2019-09-29 14:16:49 +0000
@@ -421,6 +421,17 @@
             elif not isinstance(value, datetime):
                 raise TypeError("Expected datetime, found %s" % repr(value))
             if self._tzinfo is not None:
+                # Python 3.6 gained support for calling the astimezone
+                # method on naive datetime objects, presuming them to
+                # represent system local time.  This is probably
+                # inappropriate for most uses of Storm, since depending on
+                # what the system local time happens to be is usually a
+                # mistake, so forbid this explicitly for now; we can always
+                # open it up later if there's a good reason.
+                if (value.tzinfo is None or
+                        value.tzinfo.utcoffset(value) is None):
+                    raise ValueError(
+                        "Expected aware datetime, found naive: %r" % value)
                 value = value.astimezone(self._tzinfo)
         return value
 
 
=== modified file 'tox.ini'
--- tox.ini	2019-09-17 09:45:08 +0000
+++ tox.ini	2019-09-29 14:16:49 +0000
@@ -2,6 +2,8 @@
 envlist =
     py27-{cextensions,nocextensions}
     py35-{cextensions,nocextensions}
+    py36-{cextensions,nocextensions}
+    py37-{cextensions,nocextensions}
 
 [testenv]
 deps =