Problems with rules

Carsten Zerbst (zerbst(at)tu-harburg(dot)de) reports a bug with a severity of 2
The lower the number the more severe it is.

Short Description
Problems with rules

Long Description
The given code is destilled from a reallife DB. All attempts to define a rule which automatically updates the column aenderungsdatum from table mitglieder on updates failed. The result was every time

psql:ruleerror:17: ERROR: query rewritten 10 times, may contain cycles

Sample Code
DROP TABLE "mitglieder";
CREATE TABLE "mitglieder" (
"mitid" int4 PRIMARY KEY,
"name" character varying(100) NOT NULL,
"vorname" character varying(100),
"aenderungsdatum" date DEFAULT 'now'
);

INSERT INTO "mitglieder" (mitid, name, vorname)
VALUES (42,'Surname','firstname');

DROP RULE "test";
CREATE RULE "test" AS
ON UPDATE TO "mitglieder" WHERE OLD.name <> NEW.name
DO UPDATE "mitglieder" SET "aenderungsdatum" = 'now' ;

UPDATE "mitglieder" SET name='Nachname' where mitid=42;

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