Not able to customise legends for histplots

[shivendra90]

In seaborn, it seems one cannot customise legends for histplots. I'm not sure about the other categorical plots, but it is possible for scatter plots.

# This works
f, ax = pt.subplots()

x = np.arange(0, 6)
y1 = np.random.randint(1, 50, 6)
y2 = np.random.randomint(1, 25, 6)

sns.scatterplot(x=x, y=y1, color="blue", ax=ax)
sns.scatterplot(x=x, y=y2, color="red", ax=ax)
ax.legend(fontsize="medium")
plt.show()

# This does not work
f, ax = plt.subplots()

sns.histplot(x=x, y=y1, ax=ax)
sns.histplot(x=x, y=y2, ax=ax)
ax.legend(fontsize="medium")

For hisplots, I get the error No handles with labels found to put in legend. Any way to have ax.legend function properly?

[mwaskom]

Duplicate of #2280