patch 8.2.4997: Python: changing hidden buffer can cause display mess up

Problem:    Python: changing hidden buffer can cause the display to be messed
            up.
Solution:   Do not mark changed lines when using another buffer. (Paul Ollis,
            closes #10437, closes #7972)

src/testdir/test_python3.vim

@@ -4061,4 +4061,40 @@ func Test_python3_fold_hidden_buffer()
   bwipe! Xa.txt
 endfunc
 
+" Test to catch regression fix #10437.
+func Test_python3_hidden_buf_mod_does_not_mess_up_display()
+  CheckRunVimInTerminal
+
+  let testfile = 'Xtest.vim'
+  let lines =<< trim END
+        set hidden number
+        new
+        hide
+        sil call setline(1, repeat(['aaa'], &lines) + ['bbbbbb'])
+        fu Func()
+        python3 << EOF
+        import vim
+        b = vim.buffers[2]
+        b[:] = ['', '']
+        EOF
+        endfu
+        norm! Gzb
+        call feedkeys(":call Func()\r", 'n')
+  END
+  call writefile(lines, testfile)
+
+  let rows = 10
+  let bufnr = term_start([GetVimProg(), '--clean', '-S', testfile], {'term_rows': rows})
+  call TermWait(bufnr, 100)
+  call assert_equal('run', job_status(term_getjob(bufnr)))
+  let g:test_is_flaky = 0
+  call WaitForAssert({-> assert_match('^  3 aaa$', term_getline(bufnr, 1))})
+  call WaitForAssert({-> assert_match('^ 11 bbbbbb$', term_getline(bufnr, rows - 1))})
+
+  call term_sendkeys(bufnr, ":qall!\<CR>")
+  call WaitForAssert({-> assert_equal('dead', job_status(term_getjob(bufnr)))})
+  exe bufnr . 'bwipe!'
+  call delete(testfile)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab