If you click on "(take)" next to "Assigned To:", the assignee changes to yourself, however the original assignee isn't added to the CC List. In most cases I encounter, this is not what is wanted: I want to signal: "I'll do this!", but still keep the original assignee "in the loop".
So clicking on "(take)" (and maybe "(edit)") should put the original assignee in the CC List. If this happens in JavaScript and not in the backend, it would also allow in those few cases where you want to remove the assignee from a bug altogether to erase his handle from CC List as well by editing it after taking/editing the assignee.
Version: unspecified
Severity: enhancement