SUMMARY
Sometimes, when adding a face tag, if the user types a few letters and uses the keyboard arrow keys to choose from the suggested names, the complete name fails to populate the tag. Only the few letters typed are used.

STEPS TO REPRODUCE
1. In Albums view, click on a photo to select it.
2. Press F3 to preview the photo.
3. Click the "Add a Face Tag" button, and then drag to draw a rectangle on the photo.
4. Notice that "Unknown" is selected in blue in the new tag's text box. Without clicking anything, type a few letters of a name, for example "mi".
5. A drop-down list of existing People tag names appears, showing names that contain the case-insensitive substring "mi". Press the down-arrow key several times, and notice the blue selection moving down the list of names. 

OBSERVED RESULT
Despite the selection of completed names in the dropdown, the text field above the dropdown still shows only "mi". If the user presses "Enter" at this time, a new People tag called "mi" will be created and assigned to the photo. This behavior is somewhat intermittent, but I can reproduce it via the exact steps above.

EXPECTED RESULT
As the down-arrow key moves the selection down the list of names, the selected name should appear in the text box at the top. When "Enter" is pressed, the selected name should be assigned to the photo. No new tag names should be created unless the user moves the selection all the way down to 'Create "mi" in People'.

SOFTWARE/OS VERSIONS
Ubuntu 20.10
digiKam 7.2.0-beta1, build date Oct 17 2020
KDE Frameworks Version: 5.74.0
Qt Version: 5.14.2