patch 8.1.2314: vi' sometimes does not select anything

Problem:    vi' sometimes does not select anything.
Solution:   Recognize an empty selection. (Christian Brabandt, closes #5183)
diff --git a/src/testdir/test_textobjects.vim b/src/testdir/test_textobjects.vim
index a3e3851..5702a6a 100644
--- a/src/testdir/test_textobjects.vim
+++ b/src/testdir/test_textobjects.vim
@@ -47,6 +47,9 @@
   set selection=exclusive
   exe "norm! fdvhi'y"
   call assert_equal('bcde', @")
+  let @"='dummy'
+  exe "norm! $gevi'y"
+  call assert_equal('bcde', @")
   set selection&vim
   bw!
 endfunc