Margins removed in baseline

When I run or save a modified README code in Jupyter, I get a different image than the generated baseline.

Example code run in a Jupyter cell:

#%%file test.py
%matplotlib inline

import matplotlib.pyplot as plt
import pytest

@pytest.mark.mpl_image_compare
def test_succeeds():
    fig = plt.figure()
    ax = fig.add_subplot(1,1,1)
    ax.plot([1,2,3])
    fig.savefig("test")
    return fig

Running test_succeeds(); in Jupyter gives resulting image and saved test.png with margins:

Next, I generate a test.py file by uncommenting the first line, commenting the second line
and then running the cell

%%file test.py
#%matplotlib inline

...

From a command prompt, in the appropriate directory I run the following to generate the baseline image:

> py.test --mpl-generate-path=baseline test.py

In the baseline folder, a comparable image called test_succeeds.png is created without margins:

Aside from the difference in sizes, I notice the baseline image uses the classic mpl style. Perhaps this is the cause for the absence in margins. I report this as an issue as it is ideal that when testing the baseline image, it should be the same image as shown and saved by Jupyter.

I tested this with Anaconda 4.2.

Reproduce the discrepancy using the Jupyter cell and the py.test --mpl-generate-path=baseline test.py command shown in the report, comparing the saved and baseline images. Trace how pytest-mpl generates baselines and how Jupyter applies Matplotlib settings; done means equivalent figures have consistent margins and style in both workflows.