nvim.Serve() does not return after exiting nvim.

[akiyosi]

After neovim/neovim@1d16bba, nvim.Serve() will not return if the following steps are taken to exit Neovim.

1. Run goneovim with the following

   /path/to/goneovim -u NONE --cmd 'set clipboard=unnamed' /path/to/file
   

2. Yank any text, then :wq

I have created a minimal program to reproduce this problem.
https://github.com/akiyosi/test-go-nvim-ui

[akiyosi]

Note that this problem is 100% reproducible on Linux; I have seen some reports of the problem occurring on Windows, but have not been able to confirm this.
Also, the problem is not reproducible on MacOS. I understand that this is because the ownership of the clipboard is different in MacOS than in other operating systems.

[akiyosi]

related: related: neovim/neovim#26743

[akiyosi]

This issue will be closed with the closing of Issue neovim/neovim#26743.