[tumblr] fix 'day' extractor

another bug caused by a383eca7

gallery_dl/extractor/tumblr.py

@@ -322,12 +322,15 @@ class TumblrDayExtractor(TumblrExtractor):
     def __init__(self, match):
         TumblrExtractor.__init__(self, match)
         year, month, day = match.group(4).split("/")
-        self.date_min = (
-            # 719163 == date(1970, 1, 1).toordinal()
-            date(int(year), int(month), int(day)).toordinal() - 719163) * 86400
+        self.ordinal = date(int(year), int(month), int(day)).toordinal()
 
     def _init(self):
         TumblrExtractor._init(self)
+
+        self.date_min = (
+            # 719163 == date(1970, 1, 1).toordinal()
+            (self.ordinal - 719163) * 86400)
+
         self.api.before = self.date_min + 86400
 
     def posts(self):