Merge pull request py-pdf#338 from kgengler/master

Fix issue py-pdf#337 - Rotate PDF fails if /Rotate is set to an IndirectObject

Author: mstamy2

PyPDF2/pdf.py

@@ -2226,7 +2226,8 @@ def rotateCounterClockwise(self, angle):
         return self
 
     def _rotate(self, angle):
-        currentAngle = self.get("/Rotate", 0)
+        rotateObj = self.get("/Rotate", 0)
+        currentAngle = rotateObj if isinstance(rotateObj, int) else rotateObj.getObject()
         self[NameObject("/Rotate")] = NumberObject(currentAngle + angle)
 
     def _mergeResources(res1, res2, resource):