Figure.update() misbehaviour in Python 2

[nicolaskruchten]

Consider the following code:

import plotly.graph_objs as go

def make_fig():
    return go.Figure(data=[
        go.Scatter(x=[1,2],y=[1,2], xaxis='x'), 
        go.Scatter(x=[2,3],y=[2,3], xaxis='x2')
    ])

fig = make_fig().update(layout= {
    'grid': {'xaxes': ['x', 'x2'], 'yaxes': ['y']}, 
    'xaxis': {'title': 'total_bill'}, 
    'xaxis2': {'matches': 'x', 'title': 'total_bill'}
})
print(fig.layout.xaxis2)

fig = make_fig().update(layout= {
    'grid': {'xaxes': ['x', 'x2'], 'yaxes': ['y'], 'yside': 'left', 'ygap': 0.1, 'xside': 'bottom'}, 
    'xaxis': {'title': 'total_bill'}, 
    'xaxis2': {'matches': 'x', 'title': 'total_bill'}
})
print(fig.layout.xaxis2)

In Python 3.6/plotly 3.7.0 it prints, as expected:

layout.XAxis({
    'matches': 'x', 'title': {'text': 'total_bill'}
})
layout.XAxis({
    'matches': 'x', 'title': {'text': 'total_bill'}
})

but in Python 2.7/plotly 3.7.0 it prints:

layout.XAxis({
    'matches': 'x'
})
layout.XAxis()

Note that the title didn't get set on the top one, and the matches didn't get set on the second one.