patch 9.1.0075: insert completion not correct when adding new leader

Problem:  insert completion not correct when adding new leader
Solution: Reset compl_curr_match to compl_shown_match
          (glepnir)

closes: #13957

Co-authored-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/insexpand.c b/src/insexpand.c
index ba66e51..d712181 100644
--- a/src/insexpand.c
+++ b/src/insexpand.c
@@ -1363,6 +1363,10 @@
     pum_display(compl_match_array, compl_match_arraysize, cur);
     curwin->w_cursor.col = col;
 
+    // After adding leader, set the current match to shown match.
+    if (compl_started && compl_curr_match != compl_shown_match)
+	compl_curr_match = compl_shown_match;
+
 #ifdef FEAT_EVAL
     if (has_completechanged())
 	trigger_complete_changed_event(cur);