possibly spurious warning in dev version of geom_boxplot

[malcolmbarrett]

import pandas as pd
from plotnine import *

penguins = pd.DataFrame({
    'species': ['Adelie'] * 3 + ['Gentoo'] * 3,
    'body_mass_g': [3750, 3800, 3250, 5200, 5000, 4800],
})

(
    ggplot(penguins, aes('species', 'body_mass_g', fill='species'))
    + geom_boxplot()
).draw()

produces

UserWarning: 
The following aesthetics were dropped during processing: ['y'].
plotnine could not infer the correct grouping.
Did you forget to specify a `group` aesthetic or to convert a numerical variable into a categorial?

the released version does not. the dev version still appears to produce the correct plot