Don't fail in kdeplot with empty data (closes #1235)
Don't fail in kdeplot with empty data (closes #1235)

mwaskom/seaborn,phobson/seaborn,arokem/seaborn,arokem/seaborn,phobson/seaborn,mwaskom/seaborn,lukauskas/seaborn,petebachant/seaborn,sauliusl/seaborn,anntzer/seaborn,lukauskas/seaborn,anntzer/seaborn