patch 8.1.2244: 'wrapscan' is not used for "gn"

Problem:    'wrapscan' is not used for "gn".
Solution:   Only reset 'wrapscan' for the first search round. (closes #5164)
diff --git a/src/testdir/test_gn.vim b/src/testdir/test_gn.vim
index 9edf0a2..098fc3d 100644
--- a/src/testdir/test_gn.vim
+++ b/src/testdir/test_gn.vim
@@ -135,8 +135,9 @@
   call assert_equal(['ABCDEFGHi'], getline(1,'$'))
   call setline('.', ['abcdefghi'])
   let @/ = 'b'
+  " this gn wraps around the end of the file
   exe "norm! 0fhvhhgngU"
-  call assert_equal(['abcdefghi'], getline(1,'$'))
+  call assert_equal(['aBCDEFGHi'], getline(1,'$'))
   sil! %d _
   call setline('.', ['abcdefghi'])
   let @/ = 'f'