don't call a function excessively...

setdefault works best for simple data types, calling the factory
function every time doesn't make sense...

ui/medashare/btv/__init__.py

@@ -196,8 +196,11 @@ def validate(torrent, basedir, with_file_hashes=None):
 
 	def apply_fun(data, fname, offset):
 		if with_file_hashes is not None:
-			hashobj, curoff = file_hashes.setdefault(fname,
-			    (with_file_hashes(), 0))
+			try:
+				hashobj, curoff = file_hashes[fname]
+			except KeyError:
+				hashobj, curoff = with_file_hashes(), 0
+				file_hashes[fname] = hashobj, curoff
 
 			if curoff == offset:
 				hashobj.update(data)