patch 8.2.2901: some operators not fully tested

Problem:    Some operators not fully tested.
Solution:   Add a few test cases. (Yegappan Lakshmanan, closes #8282)
diff --git a/src/testdir/test_cpoptions.vim b/src/testdir/test_cpoptions.vim
index 02cadf4..caf82ee 100644
--- a/src/testdir/test_cpoptions.vim
+++ b/src/testdir/test_cpoptions.vim
@@ -167,6 +167,7 @@
   call assert_beeps('normal "ayl')
   " change an empty line
   call assert_beeps('normal lcTa')
+  call assert_beeps('normal 0c0')
   " delete an empty line
   call assert_beeps('normal D')
   call assert_beeps('normal dl')