non_neg_mask not work

[jasstionzyf]

as i read loss function, notice:

b. get non-negative mask

non_neg_mask = tf.fill(tf.shape(labels), -1.0, name='non_neg')
non_neg_mask = tf.cast(tf.not_equal(labels, non_neg_mask), tf.float32)
tf.summary.histogram('non_neg', non_neg_mask)

but based on above code , non_neg_mask is alwayes like : [1,1,1,1,1,1,1]
wonder non_neg_mask is useless?