Data loss when "moving" a projects between two shards that have the same path

While performing some tests I unknowingly moved a project between two shards with different names but equal path (in staging.gitlab.com we have several storages but only one actual mount-point). The result is that the repository was deleted. This happens either with Gitaly on or off. We should add a simple validation to not perform any operation in this case. I'm assuming the cause is that in a normal repository storage change the "old" path is archived, but in this case that's the same as the new path.

Notice that validating that storage_path_old != storage_path_new is not fool-proof, since the same actual file could have two different mountpoints, so I'm not sure how worthwhile it is to add this validation, since the configuration of staging.gitlab.com is not usual anyways, but since it could lead to data loss in a misconfigured instance I think it's worth to think about.