Some float equality constraints are ignored

[sbronson]

% f.mzn
var 1.0..2.0: x;
var 1.0..2.0: y;
constraint x = 1.0;
constraint x = y;
solve maximize x;

$ minizinc f.mzn
x = 2.0;
y = 2.0;
----------
==========

I expected x and y to be 1.0. I'm using minizinc 2.5.3 from the Ubuntu 21.04 repositories.

[Dekker1]

The intermediate FlatZinc (generated for Gecode) is wrong:

var 1.0..2.0: x:: output_var;
solve  maximize x;