Bramify this... work around the stupidity that is BEP-52

in most cases, keys are us-ascii, but BEP-52 allows some
keys to be binary data..  It does appear that it only applies to
dictionaries that are under 'piece layer', so pass down the parent
key, and don't do encoding for the dictionary that is under it.

It also had a bug where if a dictionary key had code points >127,
it'd encode the values incorrectly, because it'd take the length of
the string and not the encoded string..

ui/medashare/btv/bencode.py

@@ -68,16 +68,23 @@ def decode_list(x, f):
         r.append(v)
     return (r, f + 1)
 
-def decode_dict(x, f):
+def decode_dict(x, f, parent=None):
     r, f = {}, f+1
     lastkey = None
     while x[f] != b'e'[0]:
         k, f = decode_string(x, f)
-        k = k.decode('us-ascii')
+        if not parent or parent not in { 'piece layers' }:
+            k = k.decode('us-ascii')
         if lastkey is not None and lastkey >= k:
             raise ValueError
         lastkey = k
-        r[k], f = decode_func[x[f]](x, f)
+
+        #decode value
+        fun = decode_func[x[f]]
+        kwargs = {}
+        if fun is decode_dict:
+            kwargs['parent'] = k
+        r[k], f = fun(x, f, **kwargs)
     return (r, f + 1)
 
 decode_func = {}
@@ -285,11 +292,18 @@ def encode_list(x,r):
             encode_func[type(e)](e, r)
         r.append(b'e')
 
-def encode_dict(x,r):
+def encode_dict(x,r, parent=None):
     r.append(b'd')
     for k,v in sorted(x.items()):
-        r.extend((b'%d:' % len(k),k.encode('UTF-8')))
-        encode_func[type(v)](v, r)
+        origk = k
+        if not parent or parent not in { 'piece layers' }:
+            k = k.encode('us-ascii')
+        r.extend((b'%d:' % len(k),k))
+        efun = encode_func[type(v)]
+        kwargs = {}
+        if efun is encode_dict:
+            kwargs['parent'] = origk
+        efun(v, r, **kwargs)
     r.append(b'e')
 
 encode_func = {}
@@ -341,6 +355,17 @@ class _TestCases(unittest.TestCase):
 
 		self.assertEqual(bencode({'': 5}), b'd0:i5ee')
 
+	def test_round_trip_files(self):
+		import importlib
+
+		fixtures = importlib.resources.files(__name__[:__name__.rindex('.')]) / 'fixtures'
+
+		for i in fixtures.iterdir():
+			with self.subTest(file=str(i)):
+				data = i.read_bytes()
+
+				self.assertEqual(data, bencode(bdecode(data)))
+
 	def test_bdecode(self):
 		test_bdecode()