Ensure body is consumed only once

[sathieu]

Fixes: #846

[sathieu]

@hartwork Please take a look at this PR :pray: .

[hartwork]

@sathieu I had a quick look and I think understand the problem now but from a quick look the patch raises questions, may not be the best place to patch yet, and is also lacking a new test to both document and regression-protect the case that it's fixing. I have other priorities at the moment, I won't be able to help more at the moment, thanks for your understanding.

[sathieu]

Thanks @hartwork I've fixed CI and added tests. Back to you :ping_pong: !

[hartwork]

Superseded by just-merged #851, closing…