Regression from 7.3 to 7.4

This testcase works in 7.3 but not in 7.4:

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create table t1 (a int);
create table t2 (b int);
select * from t1, (select b as a from t2 group by a) as foo;
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ERROR:  column "t2.b" must appear in the GROUP BY clause or be used in an 
aggregate function

I don't know if it's supposed to work to do a group by of an alias, but 
why not and it used to work.

--
/Dennis Björklund