odd bug in integrate: using x(t) instead of x get answer



s:  1/sqrt(log(x)+a*x+b)

integrate(s,x)   --> not integrated.

u:  subst(x(t),x,s);

integrate(u,x(t))   --> integrated, but maybe nonsense.

The answer looks ok if a=b=0.

Also, if a=0, the integral can be done  (correctly).