Demonstrate failure to load with custom metrics defined

keras-test-case.py

from keras.models import load_model, Sequential
from keras.layers import Dense

def x(y_true, y_pred):
    return 0.0 * y_pred

model = Sequential([
    Dense(1, input_dim=1),
])
model.compile(optimizer='rmsprop',
	          loss='categorical_crossentropy',
              metrics=[x])
model.save('somefile')
break_here = load_model('somefile')