Fixed string format specifier for fillfactor in GistIndex.

django/contrib/postgres/indexes.py

@@ -96,5 +96,5 @@ class GistIndex(PostgresIndex):
         if self.buffering is not None:
             with_params.append('buffering = %s' % ('on' if self.buffering else 'off'))
         if self.fillfactor is not None:
-            with_params.append('fillfactor = %s' % self.fillfactor)
+            with_params.append('fillfactor = %d' % self.fillfactor)
         return with_params