patch 8.2.2870: CmdlineChange event triggered twice for CTRL-R

Problem:    CmdlineChange event triggered twice for CTRL-R.
Solution:   Return CMDLINE_NOT_CHANGED from cmdline_insert_reg().
            (closes #8219)
diff --git a/src/ex_getln.c b/src/ex_getln.c
index 4ebc341..e7d71a5 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -1253,8 +1253,11 @@
 	}
 #endif
     }
+    // remove the double quote
     redrawcmd();
-    return CMDLINE_CHANGED;
+
+    // The text has been stuffed, the command line didn't change yet.
+    return CMDLINE_NOT_CHANGED;
 }
 
 /*