You could write a function like this

def arange_endpoint(start,stop,step):
    L = stop-start
    n = int(L/step)
    stop_ = start+n*step
    return np.linspace(start,stop_,n+1)

It will adapt the stop (endpoint) to the closest one smaller or equal to the provided one, see these examples:

arange_endpoint(3, 10.4, .5)
>>> array([ 3. ,  3.5,  4. ,  4.5,  5. ,  5.5,  6. ,  6.5,  7. ,  7.5,  8. ,
            8.5,  9. ,  9.5, 10. ])

arange_endpoint(3, 10.5, .5)
>>> array([ 3. ,  3.5,  4. ,  4.5,  5. ,  5.5,  6. ,  6.5,  7. ,  7.5,  8. ,
            8.5,  9. ,  9.5, 10. , 10.5])