patch 8.2.3940: match highlight disappears when doing incsearch for ":s/pat"

Problem:    Match highlight disappears when doing incsearch for ":s/pat".
Solution:   Only use line limit for incsearch highlighting. (closes #9425)
diff --git a/src/match.c b/src/match.c
index 40f426e..3b5c18e 100644
--- a/src/match.c
+++ b/src/match.c
@@ -427,7 +427,7 @@
     int		called_emsg_before = called_emsg;
 
     // for :{range}s/pat only highlight inside the range
-    if (lnum < search_first_line || lnum > search_last_line)
+    if ((lnum < search_first_line || lnum > search_last_line) && cur == NULL)
     {
 	shl->lnum = 0;
 	return;