== Summary
Code which writes to the CheckUser result tables should write a value for the `agent_id` column, as the default value of `0` means that the column needs population (as opposed to it's final value)
The `populateCheckUserData.php` should write an empty User-Agent when populating rows from the `recentchanges` table, as the default value of `0` means the row needs population (as opposed to it being it's final value)
== Background
* {T361198} is creating a maintenance script that populates the `agent_id` columns in the CheckUser result tables
** This looks for a value of `0` to determine if the column needs populating
** However, the default value of this column is `0` and so `populateCheckUserData.php` (along with other code that writes to these tables) needs to ensure that the value is set to be the `cu_useragent` value for an empty user agent
* Updating the `CheckUserInsert` service was done in {T361174} which handles most places that data is written to these tables
== Acceptance criteria
* [ ] All code which writes to the CheckUser result tables populates a value for the `agent_id` column when the user agent migration is set to write new