runtime(netrw): diff (df) may open the wrong window (#13275)

closes: #11359

Signed-off-by: Christian Brabandt <[email protected]>

Author: KSR-Yasuda

runtime/autoload/netrw.vim

@@ -7392,8 +7392,7 @@ fun! s:NetrwMarkFileDiff(islocal)
      exe "NetrwKeepj e ".fnameescape(fname)
      diffthis
     elseif cnt == 2 || cnt == 3
-     vsplit
-     wincmd l
+     below vsplit
 "     call Decho("diffthis: ".fname,'~'.expand("<slnum>"))
      exe "NetrwKeepj e ".fnameescape(fname)
      diffthis