patch 8.0.1831: sometimes the quickfix title is incorrectly prefixed with ':'

Problem:    Sometimes the quickfix title is incorrectly prefixed with ':'.
Solution:   Prepend the colon in another way. (Yegappan Lakshmanan, closes
            #2905)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index ea5ff8a..5cee976 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -10473,7 +10473,7 @@
 	}
 
 	if (l != NULL && action && valid_dict && set_errorlist(wp, l, action,
-	    (char_u *)(wp == NULL ? "setqflist()" : "setloclist()"), d) == OK)
+	  (char_u *)(wp == NULL ? ":setqflist()" : ":setloclist()"), d) == OK)
 	    rettv->vval.v_number = 0;
     }
 #endif