patch 8.0.1427: the :leftabove modifier doesn't work for :copen

Problem:    The :leftabove modifier doesn't work for :copen.
Solution:   Respect the split modifier. (Yegappan Lakshmanan, closes #2496)

src/quickfix.c

@@ -3222,6 +3222,8 @@ ex_copen(exarg_T *eap)
     }
     else
     {
+	int flags = 0;
+
 	qf_buf = qf_find_buf(qi);
 
 	/* The current window becomes the previous window afterwards. */
@@ -3229,10 +3231,14 @@ ex_copen(exarg_T *eap)
 
 	if ((eap->cmdidx == CMD_copen || eap->cmdidx == CMD_cwindow)
 		&& cmdmod.split == 0)
-	    /* Create the new window at the very bottom, except when
+	    /* Create the new quickfix window at the very bottom, except when
 	     * :belowright or :aboveleft is used. */
 	    win_goto(lastwin);
-	if (win_split(height, WSP_BELOW | WSP_NEWLOC) == FAIL)
+	/* Default is to open the window below the current window */
+	if (cmdmod.split == 0)
+	    flags = WSP_BELOW;
+	flags |= WSP_NEWLOC;
+	if (win_split(height, flags) == FAIL)
 	    return;		/* not enough room for window */
 	RESET_BINDING(curwin);
 

src/testdir/test_quickfix.vim

@@ -3078,3 +3078,30 @@ func Test_lvimgrep_crash()
   augroup END
   enew | only
 endfunc
+
+" Test for the position of the quickfix and location list window
+func Test_qfwin_pos()
+  " Open two windows
+  new | only
+  new
+  cexpr ['F1:10:L10']
+  copen
+  " Quickfix window should be the bottom most window
+  call assert_equal(3, winnr())
+  close
+  " Open at the very top
+  wincmd t
+  topleft copen
+  call assert_equal(1, winnr())
+  close
+  " open left of the current window
+  wincmd t
+  below new
+  leftabove copen
+  call assert_equal(2, winnr())
+  close
+  " open right of the current window
+  rightbelow copen
+  call assert_equal(3, winnr())
+  close
+endfunc

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1427,
 /**/
     1426,
 /**/