CircleCI slack webhooks doesn't works

[rhaamo]

Tried to use with CircleCI, getting Error: Hook failed. on CircleCI side.

Logs says Invalid message: missing text or attachments.

By using tcpdump I see the json as: {"attachments":[{"fallback":"Hello from CircleCI","text":"Hello from CircleCI","color":"#AAAAAA"}],"text":"","channel":""}

Shouldn't that already be covered by #17 or #32 ?

Running latest turt2live/matrix-appservice-webhooks:latest docker image.