Subcircuit of length 1?

[Wout4]

I am wondering about the semantics of subcircuit.
I thought there had to be a subcircuit of at least length 2 in the given array, but solving the following model in the IDE shows that an array where every element is self referencing is also a valid subcircuit. subcircuit([1,2,3]) is true
Is this intended?

include "globals.mzn";
int: n = 3;
array [1..n] of var 1..n: q;
constraint subcircuit(q);
constraint q[1] = 1;
constraint q[2] = 2;

solve satisfy;

[matsc-at-sics-se]

AFAIK the constraint does not require there to be a subcircuit of length at least 2.

[Wout4]

I think I am confused because the documentation says: Constrains the elements of x to define a subcircuit where x [ i ] = j means that j is the successor of i and x [ i ] = i means that i is not in the circuit. so if x[i] = i for all x, then there is no circuit?