Have a "Feature Toggle" to allow reports to be checked in and out.

When downloading you could have a box asking if you want to check the report out. Then when uploading it would automatically check the document in for you.

If you are downloading or uploading a report that has been checked out by another user it could warn you that the report is checked out by another user. It wouldn't stop you downloading or uploading, just a warning. If you are uploading and someone else uploaded a report when you had it checked out it could warn you that someone else had uploaded when checked out by you.

This would be good for ensuring there is no over writing of changes being made. Also when refreshing DEV and UAT environments it would indicate which reports might be wiped.