When the ComboBox currentText() was changed by key
LineUp or LineDown or mouse click, the completer still
contained the last inserted characters.
If now all text was selected (by Ctrl+A or selectAll()),
the old item and index was restored on next Enter press.
Task-number: QTBUG-41288
Change-Id: I6916fd31c8b8fbacfb12e1a62c3e46823cf918b4
Reviewed-by: Timur Pocheptsov <Timur.Pocheptsov@digia.com>