meta_request deletes keys from activesupport notification payloads

[cpb]

While it is true that payload is mutable, I for one would like to think the payload is append only. Certainly, at least, for fields written by rails itself.

So, it was with some surprise that I discovered that meta_request was the source of the mutation to the Active Support Notification payloads I was working with.

Helped explain for me the differences in my platform behaviour between test and staging vs development.

https://github.com/dejan/rails_panel/blob/master/meta_request/lib/meta_request/app_notifications.rb#L19-L25