a bug in minimize_constrained

edit

for the following code:

f = lambda x: (1-x)^(1-x)
c_1 = lambda x: x - 0.5
c_2 = lambda x: - x + 0.99
minimize_constrained(f,[c_1, c_2],[0.75])

I get:

(1.7499)

(I'm using Version 6.4.1).

Clearly, the result does not satisfy the constraints. Am I doing anything wrong? (find_minimum would not work for me, because I need to minimize a constrained 3-variable function -- this is just a 1D part of the function which results in a wrong anwer)