Fix jedi#add_goto_window: use :copen to go to the qf window always

Without this it would not go there with an already open qf window, and
would go to an unexpected buffer line instead of selecting the entry.

This is a follow-up to b689409, where it was decided that it should
always require the user to select an entry.

An exception is when the same usages are used again: then it will select
the nearest/current entry only (via ":cc").

autoload/jedi.vim

@@ -479,31 +479,23 @@ endfunction
 function! jedi#add_goto_window(for_usages, len) abort
     let height = min([a:len, g:jedi#quickfix_window_height])
 
-    " Using :cwindow allows to stay in the current window in case it is opened
-    " already.
-    let win_count = winnr('$')
-    execute 'belowright cwindow '.height
-    let qfwin_was_opened = winnr('$') > win_count
+    " Use :copen to go to the window always - the user should select an entry.
+    execute 'belowright copen '.height
 
-    if qfwin_was_opened
-        if &filetype !=# 'qf'
-            echoerr 'jedi-vim: unexpected ft with current window, please report!'
-        endif
-        if g:jedi#use_tabs_not_buffers == 1
-            noremap <buffer> <CR> :call jedi#goto_window_on_enter()<CR>
-        endif
-
-        augroup jedi_goto_window
-            if a:for_usages
-                autocmd BufWinLeave <buffer> call jedi#clear_usages()
-            else
-                autocmd WinLeave <buffer> q  " automatically leave, if an option is chosen
-            endif
-        augroup END
-    elseif a:for_usages && !s:supports_buffer_usages
-        " Init current window.
-        call jedi#_show_usages_in_win()
+    if &filetype !=# 'qf'
+        echoerr printf('jedi-vim: unexpected ft with current window (%s), please report!', &filetype)
     endif
+    if g:jedi#use_tabs_not_buffers == 1
+        noremap <buffer> <CR> :call jedi#goto_window_on_enter()<CR>
+    endif
+
+    augroup jedi_goto_window
+        if a:for_usages
+            autocmd BufWinLeave <buffer> call jedi#clear_usages()
+        else
+            autocmd WinLeave <buffer> q  " automatically leave, if an option is chosen
+        endif
+    augroup END
 
     if a:for_usages && !has('nvim')
         if s:supports_buffer_usages

pythonx/jedi_vim.py

@@ -473,12 +473,12 @@ def show_goto_multi_results(definitions, mode):
             and VimCompat.can_update_current_qflist_for_context(qf_context)):
         # Same list, only adjust title/selected entry.
         VimCompat.setqflist_title(qf_title)
+        vim_command('%dcc' % select_entry)
     else:
         VimCompat.setqflist(lst, title=qf_title, context=qf_context)
         for_usages = mode == "usages"
         vim_eval('jedi#add_goto_window(%d, %d)' % (for_usages, len(lst)))
-
-    vim_command('%d' % select_entry)
+        vim_command('%d' % select_entry)
 
 
 def _same_definitions(a, b):