The last release added the ability to specify a custom field & value that should be updated. It would be lovely to have the ability to specify that the new value should be appended. My specific use case is for a custom field that allows multiple build IDs to be entered (behaves like Labels or Fix Version/s, in that it supports multiple entries, displays them as tags).
We track Fix Versions as the overall release (i.e. - 1.9.0), and Fix Builds as the builds that the ticket is included within (i.e. - 126.96.36.199).