Fixed bug caused by microseconds being stored as floats on python2.

Author: gnattishness

pendulum/duration.py

@@ -79,7 +79,8 @@ def __new__(
         if total < 0:
             m = -1
 
-        self._microseconds = round(total % m * 1e6)
+        # round returns a float in python2, so ensure stored as an int
+        self._microseconds = int(round(total % m * 1e6))
         self._seconds = abs(int(total)) % SECONDS_PER_DAY * m
 
         _days = abs(int(total)) // SECONDS_PER_DAY * m
@@ -275,7 +276,7 @@ def to_iso8601_string(self):
             # no division to avoid possible floating point errors
             if not s:
                 s = "0"
-            s += ".{:0>6}".format(self.microseconds).rstrip("0")
+            s += ".{:0>6d}".format(self.microseconds).rstrip("0")
         if s:
             time += "{}S".format(s)
         if len(time) > 1: