pa2b2 small oddity

[Helge Gabert]

I noticed that pa2b2 does not return a solution for the prime p=2. "Error bad argument value." Why should that be, as the solution is [1 1], or (1+i)*CONJ(1+i), and clearly a sum of two squares. It is no big deal, but I am curious as to why the restriction for pa2b2 is only for primes congruent to 1 mod 4, and not also for p=2.