update incompatibility for python None. vim/vim#2246 autozimu/Languag…

…eClient-neovim#151

README.md

@@ -58,6 +58,8 @@ Note that `neovim_rpc#jobstart` only support these options:
 ## Incompatibility issues
 
 - Cannot pass `Funcref` object to python client. Pass function name instead.
+- Python `None` will be converted to `''` instead of `v:null` into vimscript.
+  See [vim#2246](https://github.com/vim/vim/issues/2246)
 - The following neovim-only API will be ignored quietly:
     - `nvim_buf_add_highlight`
     - `nvim_buf_clear_highlight`

pythonx/neovim_rpc_protocol.py

@@ -34,6 +34,8 @@ def handler(obj):
                 return vim.buffers[msgpack.unpackb(obj.data)]
             if obj.code == WINDOW_TYPE_ID:
                 return vim.windows[msgpack.unpackb(obj.data) - 1]
+        elif obj is None:
+            return ''
         if sys.version_info.major!=2:
             # python3 needs decode
             obj = decode_if_bytes(obj)