Resolve an AttributeError when calling between (#39)

* Resolve an AttributeError on `_datetime`

This seemed to be caused by passing two Pendulum objects created by `pendulum.instance(... datetime ...)` to `pendulum.now().between(...)`. Removing this explicit conversion prevents a double conversion caused by the `__gt__` method, which raised an AttributeError (because, of course, native DT objects, already extracted, will not contain a `_datetime` attribute).

This bug was at least found in pendulum 0.5.4 on python 2.7, my local dev environment for my current project.

* Unit test against Issue #39

Author: klardotsh

pendulum/pendulum.py

@@ -1166,9 +1166,6 @@ def between(self, dt1, dt2, equal=True):
 
         :rtype: bool
         """
-        dt1 = self._get_datetime(dt1)
-        dt2 = self._get_datetime(dt2)
-
         if dt1 > dt2:
             dt1, dt2 = dt2, dt1
 

tests/pendulum_tests/test_comparison.py

@@ -2,6 +2,7 @@
 
 import pytz
 from datetime import datetime
+from time import sleep
 from pendulum import Pendulum
 
 from .. import AbstractTestCase
@@ -294,6 +295,15 @@ def test_between_not_equal_switch_false(self):
         self.assertFalse(d1.between(d3, d2, False))
         self.assertFalse(d1.between(d5, d4, False))
 
+    def test_between_issue_39(self):
+        old = Pendulum.instance(datetime.utcnow())
+        sleep(0.2)
+        mid = Pendulum.now('UTC')
+        sleep(0.2)
+        new = Pendulum.instance(datetime.utcnow())
+
+        self.assertTrue(mid.between(old, new))
+
     def test_min_is_fluid(self):
         d = Pendulum.now()
         self.assertIsInstanceOfPendulum(d.min_())