MacOSX backend does not seem to be closing properly when plot windows are closed.

import matplotlib.pyplot as plt

plt.plot(range(10))
plt.show()
print("Won't reach here")
plt.plot(range(20))
plt.show()

The python script will halt after the first plt.show() even after closing the plot windows. Problem seems to be that the backend NSApp is not quitting and is not returning back from show().