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To elaborate Sebastien's answer, which is quite correct :

sage: foo=log(1+(1/(x^2+1))).integrate(x) ; foo
x*log(1/(x^2 + 1) + 1) + 2*sqrt(2)*arctan(1/2*sqrt(2)*x) - 2*arctan(x)
sage: bar=log(1+(1/(x^2+1))).integrate(x, algorithm="sympy") ; bar
x*log(1/(x^2 + 1) + 1) + 2*sqrt(2)*arctan(1/2*sqrt(2)*x) - 2*arctan(x)
sage: bool(bar==foo)
True

Maxima and Sympy get the same primitive. But

sage: foo.limit(x=oo)
-pi + sqrt(2)*pi

Correct.

sage: foo.limit(x=-oo)
pi - sqrt(2)*pi

Also correct

sage: foo.limit(x=oo)-foo.limit(x=-oo)
-2*pi + 2*sqrt(2)*pi

Still correct.

sage: log(1+(1/(x^2+1))).integrate(x,-oo,oo)
2*pi - 2*sqrt(2)*pi

Wrong. Maxima's problem isn't about primitive determination, but its use...