When merging a project version into another project version, the version history in Jira is deleted. It would be really good to store version history on the All Projects section, in addition to the change history being stored against the issues.
Adding this feature would help us a lot keeping track of the releases. For example, it would be easy to find out what versions has been merged etc. My suggestion is to store the history of the versions in the database. Use the "All projects" -> "Versions" screen to show the history of the versions in a project. For example it could say; Version 1.1 is merged to Version 1.2.