That does change things, I agree.

However, to play devil's advocate a bit: the FBI essentially saw the output of the PHP call `print_r($_SERVER)`. The only thing that's actually sensitive in there is the server's IP address and hostname. This is not usually considered sensitive information. If it is to be believed that is as far as they went before getting a warrant (and I don't know if that's the case or not), then obtaining the IP address would allow them to actually serve a court order to the hosting provider. In that sense it could be seen as non-invasive and purely conducive to their investigation.

But I agree there should not be a double standard. I think what weev did was not illegal, and what the FBI did here was not illegal, personally.

I remember reading rumors that this happened to some random user when the site went a bit wrong and they posted the information to the SR forums. I think it then got deleted fast.

Could that have been the source of the ip leak?

A search warrant isn't a license for law enforcement to break the law; it's a license to lawfully conduct a search and seizure based on probable cause of the commission of a crime. Warrants exist because of the Fourth Amendment, which /specifically/ deals with searches and seizures; warrants have nothing to do with a nonexistent general rule preventing law enforcement from breaking any law. Law enforcement can and does break the law all the time to conduct sting operations regarding drugs, prostitution, child porn, hitmen, etc.

For instance, the DEA can buy drugs in order to trace and later apprehend drug suppliers. They don't need a warrant to do this (though information gained from such a sting operation may later lead to a judge issuing a search warrant).