Running :Coclist diagnostics fails

[Curtis Spencer]

When I try to run the rls diagnostics using :Coclist diagnostics, I get the following error in the logs:

'Vim:E117: Unknown function: coc#util#set_buf_var'

Here are the top level versions:
vim version: NVIM v0.3.7
node version: v10.13.0
coc.nvim version: 0.0.72-89a83c1d29
term: xterm-256color
platform: linux

[Qiming zhao]

Please use Plug 'neoclide/coc.nvim', {'branch': 'release'} to install coc.nvim.