GP: algdep() bug?

[Michael Somos <somos@grail.cba.csuohio.edu>]

Pari Developers,

I don't know if this is exactly a bug, but perhaps there is some
other explanation why it won't find the polynomial :

? \v
                    GP/PARI CALCULATOR Version 2.2.3 (development)
                    UltraSparc (MicroSparc kernel) 32-bit version
                 (readline v2.2 enabled, extended help not available)
? p=x^8+1+9424*(-x^7+x^5+x^3-x)+7740*(x^6+x^2)+15494*x^4;
? p2=subst(p,x,I*x^2);
? rp=polroots(p);
? r_7=rp[7];
? print(p==algdep(r_7,8));
1
? rp2=polroots(p2);
? r2_7=rp2[7];    
? print(algdep(r2_7,16));
  ***   precision too low in lindep.
? \p4000
   realprecision = 4007 significant digits (4000 digits displayed)
? rp2=polroots(p2);
? r2_7=rp2[7];
? print(algdep(r2_7,16));
  ***   precision too low in lindep.
? quit

It seems to me that 4000 digits should be enough, but I have been
wrong before. Shalom, Michael