Merge pull request #3217 from radarhere/pop

Simplified dictionary pop

Author: hugovk

src/PIL/Image.py

@@ -1915,9 +1915,7 @@ def save(self, fp, format=None, **params):
         # may mutate self!
         self.load()
 
-        save_all = False
-        if 'save_all' in params:
-            save_all = params.pop('save_all')
+        save_all = params.pop('save_all', False)
         self.encoderinfo = params
         self.encoderconfig = ()