BUG: hist plot secondary-y doesn't work

[TomAugspurger]

The labels overlap

In [1]: df = pd.DataFrame(np.random.randn(30, 4), columns=list('abcd'))

In [2]: ax = df.a.plot(legend=True)

In [3]: df.b.plot(ax=ax, legend=True)
Out[3]: <matplotlib.axes._subplots.AxesSubplot at 0x10938f6a0>

[TomAugspurger]

Actually not specific to hist.

[sinhrks]

After #9812: Because the code above seems to be different, I've used following code:

df = DataFrame(np.random.randn(30, 4), columns=list('abcd'))

# primary -> secondary
ax = df['a'].plot(kind='hist', legend=True)
df['b'].plot(kind='hist', ax=ax, legend=True, secondary_y=True)