Fix typo

Author: dhirschfeld

pandas/tseries/holiday.py

@@ -412,7 +412,7 @@ def holidays(self, start=None, end=None, return_name=False):
         # get them again
         if self._cache is None or start < self._cache[0] or end > self._cache[1]:
             for rule in self.rules:
-                holidays.append(rule.dates(start, end, return_name=True)
+                holidays.append(rule.dates(start, end, return_name=True))
 
             if holidays:
                 holidays = concat(holidays)