JOSM offers to use open changeset from a different server
- Successfully open a changeset on server A and fail to close it (see #3641)
- Switch to a different server B in preferences
- Try to upload again to server B this time
- JOSM will offer to to use an open changeset from server A
Preferably JOSM should be more server aware (see #2710) and track open changeset on a per-server basis.
If I take JOSM up on its offer to upload to the open changeset on server A to server B it will detected a conflict, see another bug I'm filing for that.