[md-autocomplete] - @md-changed being called twice.

[xxRockOnxx]

Steps to reproduce

1. Copy demo code
2. add console.log as the first line of getCountries
3. type on the input

What is expected?

"fetch" be called once.

What is actually happening?

"fetch" method being called twice.

Reproduction Link

None. Copying even the demo code on the docs does not work on template.