FlurlRequest SendAsync adds an extra space to Content-Type

[AeonLucid]

Note, I am currently using the master-3.x branch.

Flurl/src/Flurl.Http/FlurlRequest.cs

Lines 165 to 177 in 9b9d899

	SyncHeaders(request);
	var call = new FlurlCall {
	Request = this,
	RedirectedFrom = _redirectedFrom,
	HttpRequestMessage = request
	};
	request.SetFlurlCall(call);
	await RaiseEventAsync(Settings.BeforeCall, Settings.BeforeCallAsync, call).ConfigureAwait(false);
	// in case URL or headers were modified in the handler above
	request.RequestUri = Url.ToUri();
	SyncHeaders(request);

When you send a HTTP POST request with the following content.

internal class CustomMediaType : MediaTypeHeaderValue
{
    public CustomMediaType() : base("application/octet-stream")
    {
    }

    public override string ToString()
    {
        return "application/octet-stream;some=b";
    }
}

new ByteArrayContent(reqBody)
{
    Headers =
    {
        ContentType = new CustomMediaType()
    }
})

What happens is, at the first SyncHeaders call it is copied from request.Content.Headers into the Headers property. This is all still fine.
Then on the second call of SyncHeaders, it copies from Headers back into request.Content through request.SetHeader, which causes it to normalize the header.

The value application/octet-stream;some=b becomes application/octet-stream; some=b, after the second SyncHeaders call.

I understand this might be a slight edge case but as you can see similar issues have been raised with the .NET team. dotnet/runtime#30171

[tmenier]

Sorry for the delay. Thanks for the details, if I understand it correctly this might be fixable.

[tmenier]

Fixed for 4.0