updated for version 7.3.489
Problem:    CTRL-] in Insert mode does not expand abbreviation when used in a
            mapping. (Yichao Zhou)
Solution:   Special case using CTRL-]. (Christian Brabandt)
diff --git a/src/getchar.c b/src/getchar.c
index dc7d768..606d9a2 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -4352,8 +4352,9 @@
 
     if (typebuf.tb_no_abbr_cnt)	/* abbrev. are not recursive */
 	return FALSE;
-    if ((KeyNoremap & (RM_NONE|RM_SCRIPT)) != 0)
-	/* no remapping implies no abbreviation */
+
+    /* no remapping implies no abbreviation, except for CTRL-] */
+    if ((KeyNoremap & (RM_NONE|RM_SCRIPT)) != 0 && c != Ctrl_RSB)
 	return FALSE;
 
     /*