Problem:
`buftype=help` occasionally propagates from help to man buffer. As a result the
next time you open help it opens in the man window, replacing the manpage.
Test case:
nvim -u NORC
:Man man
:set bt? " should print `buftype=nofile`
:help
<C-W><C-W><C-W>c " go back to :Man window and close it
:help " focus help window
:Man man " open window with manpage again
:set bt? " prints `buftype=help`
Solution:
- call s:set_options()
- man#read_page() (called by autocmd BufReadCmd man://*) should already do
this. But BufReadCmd doesn't fire for already-existing man:// buffers.
Fix#15650
29bc648d2b
