ValueError in HillClimbSearch().estimate()

[Kuril951]

Subject of the issue

It raises ValueError when estimating the graph with the HillClimbSearch model.

Your environment

• pgmpy version : 0.1.12
• Python version : 3.7.7
• Operating System : Ubuntu 18.04.2 LTS

Steps to reproduce

data = pd.DataFrame(
        [[1,0,0,1,0,0,1,1,0],
         [1,0,1,0,0,1,0,1,0],
         [1,0,0,0,0,1,0,1,1],
         [1,1,0,1,0,1,1,0,0],
         [0,0,1,0,0,1,1,0,0]],
        columns=list('ABCDEFGHI')
    )
est = HillClimbSearch(data)
best_model = est.estimate(
    fixed_edges=[('A','B'), ('B', 'C')],
    white_list=[('F','C')]
)

Expected behaviour

1. return model with fixed edges
   or
2. return model with fixed_edges and white_list edges

Actual behaviour

[ankurankan]

@Kuril951 If you install the latest dev branch this should work now.