patch 8.0.1733: incomplete testing for completion fix

Problem:    Incomplete testing for completion fix. (Lifepillar)
Solution:   Add a test with CTRL-P.

src/testdir/test_popup.vim

@@ -824,4 +824,14 @@ func Test_popup_complete_backwards()
   bwipe!
 endfunc
 
+func Test_popup_complete_backwards_ctrl_p()
+  new
+  call setline(1, ['Post', 'Port', 'Po'])
+  let expected=['Post', 'Port', 'Port']
+  call cursor(3,2)
+  call feedkeys("A\<C-P>\<C-N>rt\<cr>", 'tx')
+  call assert_equal(expected, getline(1,'$'))
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -762,6 +762,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1733,
 /**/
     1732,
 /**/