Combobox filter bug?

Hi!

When I place a filter in the combobox, for example, the letter 't', it expands and displays words beginning with "t".

But if we clear all the words of the field, instead of showing the full combobox list, still only show the words starting with 't', only coming out of this state if we give a space with tab.

It's a bug?

Fiddle:

http://ift.tt/1zLF8kL

Combobox filter bug?