[IMPR] Simplify month_delta test in apply_month_delta

Change-Id: Iff0679ff62dba9f51be604e55b0bc539fec6beaa
---
M pywikibot/date.py
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pywikibot/date.py b/pywikibot/date.py
index fb761cb..aecefd1 100644
--- a/pywikibot/date.py
+++ b/pywikibot/date.py
@@ -2360,7 +2360,7 @@
     @return: The end date
     @rtype: type of date
     """
-    if int(month_delta) != month_delta:
+    if not isinstance(month_delta, int):
         raise ValueError('Month delta must be an integer')
     month = (date.month - 1) + month_delta
     year = date.year + month // 12

