Editable QComboBox::setCurrentText and selectAll() changes currentIndex on enter key pressed

Hello,

Problem: 

I am adding text to editable QComboBox with setCurrentText() and then selectAll(). When the user presses Enter, it should validate the input.

What is currently happening: it works for the first time but then it always goes back to the first index.

Test case:

I attach small test case (available on github https://github.com/p4lewandowski/QComboBox_bug): 

1. Click on "Add entry" button (focus is given back to QComboBox).
2. Press Enter to validate string (it works).
3. Click on "Add entry" again.
4. Press Enter to validate
   1. Display text is changed back to first input.
   2. You can check in the console QComboBox::currentText() is changed too.

Use of selectAll() in my application is required to ease the next input.

Similar issue without setCurrentText(), fixed, can be found here: https://bugreports.qt.io/browse/QTBUG-41288?jql=text%20~%20%22qcombobox%20selectall%22