emptyMessage appears before minLength is reached in autoComplete

[wsz34]

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Plunkr Case (Bug Reports)
http://plnkr.co/edit/fw41pIZ1tojfLoTEi1tg?p=preview

Current behavior
emptyMessage appears before minLength is reached in autoComplete component

Expected behavior
emptyMessage should be shound only if search does not return any results

Minimal reproduction of the problem with instructions
Open http://plnkr.co/edit/fw41pIZ1tojfLoTEi1tg?p=preview
Run it
Start typing "test"
Notice that after first symbol message "No results found" appears (minLength is set to 3)
Continue typing
Notice that after entered "tes", one result is found ("Test")

I believe that before search method is called, emptyMessage should not be shown to user.

• Angular version: 4.1.3
• PrimeNG version: 4.1.0-RC3
• Browser: all
• Language: all