How to factor integer over Z[i]?

[Andrew Lelechenko <andrew.lelechenko@gmail.com>]

I can factor an integer over the ring of integers and I can factor a
Gaussian integer over the ring of Gaussian integers:

? factor(25)
%5 =
[5 2]
? factor(5+I)
time = 0 ms.
%2 =
[     -I 1]
[  1 + I 1]
[2 + 3*I 1]

But how should I ask PARI/GP to factor an integer over Gaussian
integers? I tried for example factor(5+0*I), but it doesn't work well.

-- 
Best regards,
Andrew