[Maxima} New defint.lisp bug

I tried this integral in Maple 15.

> restart;assume(n>0, a>0, b>a);
integrate(exp(x^n),x=a..b);
                                  b~
                                 /
                                |         n~
                                |    exp(x  ) dx
                                |
                               /
                                 a~

evalc(%);
   b~
  /
 |
 |    exp(exp(n~ ln(| x |)) cos(n~ (1/2 - 1/2 signum(x)) Pi))
 |
/
  a~

    cos(exp(n~ ln(| x |)) sin(n~ (1/2 - 1/2 signum(x)) Pi)) dx

expand(%);
                                   n~          n~
                         -a~ exp(a~  ) + exp(b~  ) b~

about({a,b,n});
{a, b, n}:
  is used in the following assumed objects
  [a] assumed RealRange(Open(0),infinity)
  [b] assumed real
  [n] assumed RealRange(Open(0),infinity)
  [-b+a] assumed RealRange(-infinity,Open(0))

Tom Dean