[Python] sympy unable to take simple integral

I'm trying to take the following integral using sympy and it won't take it:

>>> from sympy import *
>>> integrate(x*exp(-(x-x0)**2), (x, 0, k))


If I 'help' it by adding and subtracting the same expression, it works fine:

>>> sp.integrate((x-x0)*sp.exp(-(x-x0)**2)+x0*sp.exp(-(x-x0)**2), (x, 0, k))


Is there any way to automate this process?

Wolfram Alpha takes it easily without any hints from user's side:

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