vim-patch:8.2.3475: expression register set by not executed put command (#17211)

src/nvim/testdir/test_excmd.vim

@@ -400,3 +400,13 @@ func Test_winsize_cmd()
   call assert_fails('win_getid(1)', 'E475: Invalid argument: _getid(1)')
   " Actually changing the window size would be flaky.
 endfunc
+
+func Test_not_break_expression_register()
+  call setreg('=', '1+1')
+  if 0
+    put =1
+  endif
+  call assert_equal('1+1', getreg('=', 1))
+endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab