Steps to Reproduce:
- Go to Special:Block
- Select "editing" and "partial" (not "sitewide")
- Leave the "pages" field empty
- Leave the "namespaces" field empty
- Unselect "block account creation"
- Unselect "autoblock any IP addresses used"
- Execute the block
- Nothing happens to the user (no block notice is shown when attempting to edit, etc)
- The block is recorded as successful, despite not doing anything
- Block fails, with a warning that the block doesn't actually prevent anything