Unneeded formatted-body being added to message content

[photosheep]

This was discussed in the iamb-users room.

"content": {
  "body": "this is fractal",
  "msgtype": "m.text"
}

"content": {
  "body": "this is iamb",
  "format": "org.matrix.custom.html",
  "formatted_body": "<p>this is iamb</p>\n",
  "msgtype": "m.text"
}

Some clients apparently do not render this properly.
Fractal and cinny do not send a formatted_body unless required. It may be worth checking the content of the body before formatting it.