In JIRA 6.1, it is possible to rename a project key. However, it is not possible to use a used project key.
- Let's say user has renamed a project key from "ABC" to "KLM"
- Although there is no project uses the project key ABC, user is not allowed to re-use "ABC" for the new project key.
- Ideally, user should be able to re-use the project key "ABC" for other/new project