Add custom labels to all imported issues
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## Problem to solve
When importing issues from another issue tracker, I would like an option to add a set of custom labels, so that I can easily find the issues that were imported.
As MVC, we could add just one label (auto-created).
## Proposed solution
In order to help users to keep track of what was imported, we can apply an `imported-<timestamp>` label to the newly imported issues.
This will give users a good way to identify the imported issues.
issue