No. But what if I was the consultant who wrote that file and I picked it particularly because it shared the hash of one of a family of malicious auto-generated

No. But what if I was the consultant who wrote that file and I picked it particularly because it shared the hash of one of a family of malicious auto-generated files I had already created? That'd still be hard but much more likely. This has implications for people who use tools like tripwire. If you didn't create the original file it might be the benign half of a set, if the details of your hashing are known to the attacker.