Uncovered while looking into NuGet issue: https://github.com/NuGet/Home/issues/3251
See notes I left in comment https://github.com/NuGet/Home/issues/3251#issuecomment-278543504
As weird as it seems to me, it looks like the use case that NuGet employs (re-sending the same StreamContent instance) is supported by, at least, corefx: https://github.com/dotnet/corefx/blob/master/src/System.Net.Http/src/System/Net/Http/StreamContent.cs#L98
I made a patch to implement this hackily and it does make NuGet push work: https://github.com/mono/mono/commit/7fe444e6b02db07563de38ba325877cbe4f5ace4
Which mono do you need this to be fixed?
Fixed in master and 2017-02