patch 9.1.1272: completion: in keyword completion Ctrl_P cannot go back after Ctrl_N

Problem:  completion: in keyword completion Ctrl_P cannot go back after
          Ctrl_N
Solution: in find_compl_when_fuzzy() always return first match of array, after Ctrl_P
          use compl_shown_match->cp_next instead of compl_first_match.
          (glepnir)

closes: #17043

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/insexpand.c b/src/insexpand.c
index de3d519..9df0445 100644
--- a/src/insexpand.c
+++ b/src/insexpand.c
@@ -4831,7 +4831,8 @@
 
     if ((is_forward && compl_selected_item == compl_match_arraysize - 1)
 	    || (is_backward && compl_selected_item == 0))
-	return compl_first_match != compl_shown_match ? compl_first_match :
+	return compl_first_match != compl_shown_match ?
+	    (is_forward ? compl_shown_match->cp_next : compl_first_match) :
 	    (compl_first_match->cp_prev ? compl_first_match->cp_prev : NULL);
 
     if (is_forward)