Unexplainable integration failure

[Emmanuel Charpentier]

Is this failure of a trivial integral known ?

>>> from sympy import symbols, Lambda, beta
>>> x, a, b = symbols("x, a, b")
>>> dgamma = Lambda((x, a, b), x**(a-1)*(1-x)**(b-1)/beta(a, b))
>>> dgamma(x, a+1, b+1).integrate((x, 0, 1)).simplify() # Works as expected
1
>>> dgamma(x, a, b).integrate((x, 0, 1)).simplify() # Never returns !

If this is not known, how to report this problem efficiently ?

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