#1182 rat/algebraic doesn't do full gcd

[Stavros Macrakis]

q: rat((%i-1)/(%i+1))$
rat(q),algebraic => 2*%i/2 ???

but

rat((%i-1)/(%i+1)),algebraic => %i

The 2's in the numerator and denominator should have cancelled.

What's more puzzling:

block([algebraic:true],rat(q)) => (%i-1)/(%i+1)

Also

algebraic:true$
rat(q) => (%i-1)/(%i+1) ??
ev(rat(q)) => 2*%i/2 ??

but

algebraic:true$
rat((%i-1)/(%i+1)) => %i

This bug shows up both in 5.11.0/gcl and 5.11.0cvs/clisp