bug: prevent creating requests if a request exists for another version #482
Description
When researchers assign an upload to our Community, then revise it and create a new version, and finally also assign this new version to the community, two separate requests appear in our Community inbox. However, when I accept one of these requests, I am unable to accept the other. An error message appears: "The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application." For users, all versions are displayed as assigned to the Community. However, this leaves the second request stuck in our inbox, with no way to remove/accept it.
In practice, users can decline the duplicate requests, but we should prevent submission of multiple versions of the same record