vim-patch:8.2.1902: default option values changed with :badd for existing buffer

Problem:    Default option values are changed when using :badd for an existing
            buffer.
Solution:   When calling buflist_new() pass a zero line number. (closes vim/vim#7195)
e974fa7b2b

src/nvim/ex_cmds.c

@@ -2324,7 +2324,9 @@ int do_ecmd(
       buf = buflist_findnr(fnum);
     } else {
       if (flags & (ECMD_ADDBUF | ECMD_ALTBUF)) {
-        linenr_T tlnum = 1L;
+        // Default the line number to zero to avoid that a wininfo item
+        // is added for the current window.
+        linenr_T tlnum = 0;
 
         if (command != NULL) {
           tlnum = atol((char *)command);

src/nvim/testdir/test_buffer.vim

@@ -1,5 +1,17 @@
 " Tests for Vim buffer
 
+func Test_badd_options()
+  new SomeNewBuffer
+  setlocal cole=3
+  wincmd p
+  badd SomeNewBuffer
+  new SomeNewBuffer
+  call assert_equal(3, &cole)
+  close
+  close
+  bwipe! SomeNewBuffer
+endfunc
+
 func Test_balt()
   new SomeNewBuffer
   balt +3 OtherBuffer