Binary pattern syntax anomaly

[Kostis Sagonas]

Is there any particularly good reason why the following piece of
Erlang code works correctly

	B = <<2,42>>,
	<<1, B/binary>> = <<1, <<2,42>>/binary>>.

while the following (semantically equivalent) code

	<<1, <<2,42>>/binary>> = <<1, <<2,42>>/binary>>.

gets rejected as an illegal pattern?

Isn't this a bug, or at least a totally unnecessary restriction
in the syntax of binary patterns?

Kostis.