Storage 'filesystem': unexpected behaviour on "read only" filesystems

[oli-h]

In cases "read-only" or "write-protected" file/directory/filesystem (or simply: not enough access rights to create/delete/modify files and/or directories) the http-Response-Codes seem to be incorrect.
Examples:

• DELETE on a write-protected file return "404 NOT FOUND" (or "200 OK" when return200onDeleteNonExisting=true) - but file/resource is not deleted
• PUT of a resource onto a write-protected directory returns "500 internal server error"

In both cases I would expect "405 Method Not Allowed"