memory leak in date_part() function in v7.1beta3 ?

Hello Developers,

at first, thank you for the wonderful work you did on the excellent
database.

I was experimenting with the 7.1beta3 release. When I use the
date_part() function in one query several thousand times (in updates for
example) the postmaster consumes all available memory, until it dies,
with a "no memory left error". If I execute the same queries without
date_part() functions everything runs smooth.

It assume that date_part() has a serious memory leak.

If you like a can reproduce some queries that fail on my machine and
send them to you with a second email.

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