The relevance is that this text could ostensibly be used as the known plaintext to aid in breaking encryption, however, it's not going help much anyway.
For example, with HTTP 1.1, it is pretty much likely that an HTTP response would start with HTTP/1.1 200 OK, or that it would contain strings such as "Content-Type" or "Content-Length". 24 more known bytes won't make it much worse.
When you have an encrypted file (or a stream for that matter) and you know the first N bytes of the decrypted data, it might be easier to compute the encryption key if algorithm uses blocks smaller than N.
