Created by: liym27

PR types: Bug fixes

PR changes: Others

Describe: 1.

• Before: Don't create logical node recursively

(x >= 0 and x < 10) or x <= -1 or x < -3 or (x < -7 or x < -5) 

The logical node: missing or (x < -7 or x < -5)

fluid.layers.logical_or(x=fluid.layers.logical_or(x=fluid.
            layers.logical_and(x=x >= 0, y=x < 10), y=x <= -1), y=x < -3)

• This PR: fix this bug

# The logical node now
fluid.layers.logical_or(x=fluid.layers.logical_or(x=fluid.
            layers.logical_and(x=x >= 0, y=x < 10), y=x <= -1), y=fluid.
            layers.logical_or(x=x < -3, y=fluid.layers.logical_or(x=x < -7,
            y=x < -5)))

• Before: The unittest doesn't expose this bug.
• This PR: Modify the unittest to check whether the recursive conversion is successful.