  Predictions of Akkermans et al. are essentially changed when the Krein
spectral displacement operator is regularized by means of zeta function.
Instead of piecewise constant persistent current of free electrons on the plane
one has a current which varies linearly with the flux and is antisymmetric with
regard to all time preserving values of $\alpha$ including $1/2$. Different
self-adjoint extensions of the problem and role of the resonance are discussed.
