expintegral_e: series failed



attempted evaluation of bfloat of an expression
involving gamma_incomplete's leads to an 
error message:
----------------------------------------------------------
Maxima 5.25.1 http://maxima.sourceforge.net
using Lisp GNU Common Lisp (GCL) GCL 2.6.8 (a.k.a. GCL)


(%i1) r:integrate(integrate(cos(x*y*log(2)),y,1,100),x,1,100);

(%o1) -(%i*gamma_incomplete(0,10000*%i*log(2))
       -2*%i*gamma_incomplete(0,100*%i*log(2))
       +%i*gamma_incomplete(0,%i*log(2))-%i*gamma_incomplete(0,-%i*log(2))
       +2*%i*gamma_incomplete(0,-100*%i*log(2))
       -%i*gamma_incomplete(0,-10000*%i*log(2))) /(2*log(2))

(%i2) block([fpprec:20],bfloat(r));

expintegral_e: series failed.
 -- an error. To debug this try: debugmode(true);

(%i3) block([fpprec:20],
          bfloat(gamma_incomplete(0,10000*%i*log(2))));

expintegral_e: series failed.
 -- an error. To debug this try: debugmode(true);
--------------------------------------------------------
My actual goal is to replace 100 by 10^4 in both upper limits.

Ted Woollett