overlordq wrote:

Likely from the fact that the all block inserts are done as INSERT IGNORE.

Since your IP is already softblocked, it has an entry in the ipblocks table, and there's a unique key constraint on ipb_address.

Whe the hardblock of A will gets submitted, it tries to go back and hardblock the last IP but it's already in the table (but without autoblock flag), and will silently fail.

So when User B comes along, autoblock isn't on for that IP.

overlordq wrote:

I take that back, I'm just an idiot, although that hasn't stopped me yet.

When it checks for blocks, the order is: User, IP, Range, Auto.

Since the IP is softblock, it's an IP anon-only block. User A, is a user block with a autoblock on the IP.

So when User B comes along with the same IP as the softblock/User A, it skips User since User B isn't blocked, it gets to IP, sees the IP is blocked, also notices that its set to anon-only so it goes "Oops, doesn't apply, lets bail" so the autoblock never gets checked.

On a side note, if User A has never edited, there will be no autoblocked IP since autoblocks use most recent contrib, if they've never edited it wont have an IP to add to ipblocks. So the autoblock wont trigger period.

This also may prove to be completely wrong as well :)

This is no longer happening: "Your IP address has been automatically blocked because it was used by another user, who was blocked by WikiSysop."