Fixed bug when updating components on a notice

After further review today we have managed to trace this bug back to a release we made on October 30th: Background preparation for platform upgrades

It seems that removing one of the 3rd party dependencies inadvertently made a subtle change to the way that agent collision was checked when customers were updating a notice.

This resulted in any changes to the components on a notice failing because the system thought the change was in conflict with another user.

Hopefully, this provides some more background, and the additional tests put in place are an assurance that it's unlikely to happen again.

Over the weekend, a customer reported a bug that prevented them from updating the components assigned to an existing planned maintenance.

After some testing, we were able to reproduce the bug, which we suspect had existed for quite some time but gone unnoticed.

We released a patch for this bug within a few hours of the initial report, and we have also added some automated tests to check this specific behaviour and ensure it does not break again in future.