fix: issue2551278 - datetime.datetime.utcnow deprecation.

Replace calls with equivalent that produces timezone aware dates
rather than naive dates.

Also some flake8 fixes for test/rest_common.py.

CHANGES.txt

@@ -34,6 +34,9 @@ Fixed:
   and make *FieldStroage symbols available. Roundp uses its own
   cgitb.py and not the system cgitb.py. It looks like it's the
   precursor to the system cgitb.py. (John Rouillard)
+- issue2551278 - datetime.datetime.utcnow deprecation. Replace
+  calls with equivalent that produces timezone aware dates rather than
+  naive dates. (John Rouillard)
 
 Features:
 

roundup/anypy/datetime_.py

@@ -0,0 +1,12 @@
+# https://issues.roundup-tracker.org/issue2551278
+# datetime.utcnow deprecated
+try:
+    from datetime import now, UTC
+
+    def utcnow():
+        return now(UTC)
+except ImportError:
+    import datetime
+
+    def utcnow():
+        return datetime.datetime.utcnow()

roundup/date.py

@@ -24,6 +24,8 @@
 import datetime
 import re
 
+from roundup.anypy.datetime_ import utcnow
+
 try:
     import pytz
 except ImportError:
@@ -376,7 +378,7 @@ def __init__(self, spec='.', offset=0, add_granularity=False,
     def now(self):
         """ To be able to override for testing
         """
-        return datetime.datetime.utcnow()
+        return utcnow()
 
     def set(self, spec, offset=0, date_re=date_re,
             serialised_re=serialised_date_re, add_granularity=False):

roundup/rate_limit.py

@@ -6,6 +6,8 @@
 
 from datetime import timedelta, datetime
 
+from roundup.anypy.datetime_ import utcnow
+
 
 class RateLimit:  # pylint: disable=too-few-public-methods
     def __init__(self, count, period):
@@ -50,7 +52,7 @@ def update(self, key, limit, testonly=False):
         '''Determine if the item associated with the key should be
            rejected given the RateLimit limit.
         '''
-        now = datetime.utcnow()
+        now = utcnow()
         tat = max(self.get_tat(key), now)
         separation = (tat - now).total_seconds()
         max_interval = limit.period.total_seconds() - limit.inverse
@@ -88,7 +90,7 @@ def status(self, key, limit):
                                           )
 
         # status of current limit as of now
-        now = datetime.utcnow()
+        now = utcnow()
 
         current_count = int((limit.period - (tat - now)).total_seconds() /
                             limit.inverse)