Python metrics cause transaction duration changes

[HazAT]

From discord (Original message):
(Flask Python app, served by Gunicorn). It looks like the existing automated, sampled transaction.duration metric went haywire around when I started sending metrics. Ironically one of the metrics I started sending was request_duration since I wanted to see the value on 100% of requests instead of sampled requests. I also noticed the duration distributions for profiles which were sampled look a lot better somehow.