If a file has been opened in the editor, it cannot then be unshelved by perforce until the editor is restarted

When the Editor launches it does not have a file lock on assets that are not open. When the asset is opened for editing, UE gets a lock on the file and this lock persists even after the tab is closed. At that point there is no way to overwrite the file (such as when unshelving changes from P4) without fully closing the Editor.

1) Check out an asset (eg. blueprint) in P4 and begin editing it in the Editor.
2) Shelve and revert the file in P4
3) In the Editor, reload the asset and open it to view the original
4) Close the tab for the asset
5) Attempt to unshelve the asset
Result: The file can not be overwritten because "it is open in Unreal Editor" even though it is not being edited. The Editor must be closed before the file can be unshelved, which is a time-consuming workflow.