use one self.transform for rotation

PIL/Image.py

@@ -30,6 +30,7 @@ from PIL import VERSION, PILLOW_VERSION, _plugins
 
 import logging
 import warnings
+import math
 
 logger = logging.getLogger(__name__)
 
@@ -1581,8 +1582,7 @@ class Image(object):
         if angle == 270 and expand:
             return self.transpose(ROTATE_270)
 
-        if expand:
-            import math
+
         angle = - math.radians(angle)
         matrix = [
             round(math.cos(angle), 15), round(math.sin(angle), 15), 0.0,
@@ -1593,8 +1593,9 @@ class Image(object):
             (a, b, c, d, e, f) = matrix
             return a*x + b*y + c, d*x + e*y + f
 
-            # calculate output size
         w, h = self.size
+        if expand:
+            # calculate output size
             xx = []
             yy = []
             for x, y in ((0, 0), (w, 0), (w, h), (0, h)):
@@ -1611,16 +1612,6 @@ class Image(object):
 
         return self.transform((w, h), AFFINE, matrix, resample)
 
-        if resample not in (NEAREST, BILINEAR, BICUBIC):
-            raise ValueError("unknown resampling filter")
-
-        self.load()
-
-        if self.mode in ("1", "P"):
-            resample = NEAREST
-
-        return self._new(self.im.rotate(angle, resample, expand))
-
     def save(self, fp, format=None, **params):
         """
         Saves this image under the given filename.  If no format is