patch 8.0.0247: need to type Ctrl-N twice to select a completion

Problem:    Under some circumstances, one needs to type Ctrl-N or Ctrl-P twice
            to have a menu entry selected. (Lifepillar)
Solution:   call ins_compl_free(). (Christian Brabandt, closes #1411)

src/edit.c

@@ -2821,6 +2821,7 @@ set_completion(colnr_T startcol, list_T *list)
     if (ctrl_x_mode != 0)
 	ins_compl_prep(' ');
     ins_compl_clear();
+    ins_compl_free();
 
     compl_direction = FORWARD;
     if (startcol > curwin->w_cursor.col)

src/testdir/test_popup.vim

@@ -482,4 +482,33 @@ func Test_completion_ctrl_e_without_autowrap()
   q!
 endfunc
 
+function! DummyCompleteSix()
+  call complete(1, ['Hello', 'World'])
+  return ''
+endfunction
+
+" complete() correctly clears the list of autocomplete candidates
+" See #1411
+func Test_completion_clear_candidate_list()
+  new
+  %d
+  " select first entry from the completion popup
+  call feedkeys("a    xxx\<C-N>\<C-R>=DummyCompleteSix()\<CR>", "tx")
+  call assert_equal('Hello', getline(1))
+  %d
+  " select second entry from the completion popup
+  call feedkeys("a    xxx\<C-N>\<C-R>=DummyCompleteSix()\<CR>\<C-N>", "tx")
+  call assert_equal('World', getline(1))
+  %d
+  " select original text
+  call feedkeys("a    xxx\<C-N>\<C-R>=DummyCompleteSix()\<CR>\<C-N>\<C-N>", "tx")
+  call assert_equal('    xxx', getline(1))
+  %d
+  " back at first entry from completion list
+  call feedkeys("a    xxx\<C-N>\<C-R>=DummyCompleteSix()\<CR>\<C-N>\<C-N>\<C-N>", "tx")
+  call assert_equal('Hello', getline(1))
+
+  bw!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    247,
 /**/
     246,
 /**/