When creating without tzinfo, preserve fold. (#108)

When creating a new Pendulum instance without passing in a TimezoneInfo
object and using python 3.6, the internal fold parameter was not
correct.  In this scenario, self._fold was being set based on the fold
parameter in the underlying datetime object.  When using python3.6, this
value exists, but is always set to 0 since Pendulum is not passing the
fold parameter to the constructor.

 - Changed self._fold to always be set based on the internal fold
   variable.
 - Added checks to the existing unit tests to verify that the fold
   parameter is being preserved.

Author: neonquill

pendulum/pendulum.py

@@ -176,7 +176,7 @@ def __init__(self, year, month, day,
             self._second = dt.second
             self._microsecond = dt.microsecond
             self._tzinfo = dt.tzinfo
-            self._fold = getattr(dt, 'fold', fold)
+            self._fold = fold
 
         self._timestamp = None
         self._int_timestamp = None

tests/pendulum_tests/test_construct.py

@@ -202,6 +202,8 @@ def test_init_fold_is_honored_if_explicit(self):
 
         d = Pendulum(2013, 3, 31, 2, 30, tzinfo='Europe/Paris', fold=0)
         self.assertPendulum(d, 2013, 3, 31, 1, 30)
+        self.assertEqual(d.fold, 0)
 
         d = Pendulum(2013, 3, 31, 2, 30, tzinfo='Europe/Paris', fold=1)
         self.assertPendulum(d, 2013, 3, 31, 3, 30)
+        self.assertEqual(d.fold, 1)