Streaming over HTTPS sends broken content

[G-Goldstein]

I don't know the full parameters of this, but I've been using flask-sse on GKE, with Gunicorn and Gevent workers. I've found that SSE over http works well, but over https gives fractured responses and doesn't push through fully.

frankxl's fork of this repo has a fix for this here: franklx@8030f48 - I don't know if there are any other implications from this fix, but it's resolved my issue.