py3: fix bytes iteration stable

py3: fix bytes iteration

--- a/hgext/convert/common.py	Mon Jun 15 03:09:55 2020 +0200
+++ b/hgext/convert/common.py	Mon Jun 15 03:30:24 2020 +0200
@@ -87,7 +87,7 @@
 def encodeargs(args):
     def encodearg(s):
         lines = base64.encodestring(s)
-        lines = [l.splitlines()[0] for l in lines]
+        lines = [l.splitlines()[0] for l in pycompat.iterbytestr(lines)]
         return b''.join(lines)
 
     s = pickle.dumps(args)