Duplicate tags are created when adding an existing Cyrillic tag

[eugene-lesnov]

Operating system

Linux

Joplin version

3.6.14

Desktop version info

Duplicate tags are created when adding an existing Cyrillic tag

Description

When I add an existing tag written in Cyrillic to several notes/tasks, Joplin creates duplicate tags with the same visible name instead of reusing the existing tag.

This does not seem to happen with Latin tag names.

Current behaviour

1. Create a tag named Посмотреть.
2. Create several notes or tasks.
3. Add the existing tag Посмотреть to each note/task.
4. Open the tags sidebar.

The sidebar shows several identical tags:

Посмотреть 1
Посмотреть 1
Посмотреть 1

SQLite confirms that these are different tag records with the same title:

079bf8365fc54f88b4dc846699792508|[Посмотреть]|10|D09FD0BED181D0BCD0BED182D180D0B5D182D18C
e6288a5cbe734b8ab796e827335f7f92|[Посмотреть]|10|D09FD0BED181D0BCD0BED182D180D0B5D182D18C

Expected behaviour

Joplin should reuse the existing tag and show one tag with the correct note count:

Посмотреть 3

Logs

No response

[mrjo118]

I can reproduce this on the Android 3.6 app (haven't tested on desktop). Interestingly when entering the tag name in the tag search, it does correctly match the existing tag. But even though you select the existing tag, for some reason it does create a separate tag which is shown in the tag list.

I've confirmed on Joplin 3.5 the issue soes not occur, so it looks like it's a regression caused by #14599