Don't overwrite the file event's path attribute

There is custom logic which doesn't overwrite the "host" attribute if it was
originally specified by the event. This commit adds it for the "path"
attribute as well.

This is especially useful, since handy Rails gems like [Lograge use the
"path" attribute for the request's path.][1]

[1]: https://github.com/roidrage/lograge/blob/c958aa9/lib/lograge/log_subscriber.rb#L34-L42