updated for version 7.4.597

Problem:    Cannot change the result of systemlist().
Solution:   Initialize v_lock. (Yukihiro Nakadaira)

src/eval.c

@@ -6007,6 +6007,7 @@ list_free(l, recurse)
 
 /*
  * Allocate a list item.
+ * It is not initialized, don't forget to set v_lock.
  */
     listitem_T *
 listitem_alloc()
@@ -18713,6 +18714,7 @@ get_cmd_output_as_rettv(argvars, rettv, retlist)
 		goto errret;
 	    }
 	    li->li_tv.v_type = VAR_STRING;
+	    li->li_tv.v_lock = 0;
 	    li->li_tv.vval.v_string = s;
 	    list_append(list, li);
 	}

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    597,
 /**/
     596,
 /**/