Incompatible with lambda environment simulation by SAM

[ichyo]

Using lambda_http from the master branch, Invoking sam local invoke or sam local start-api returns the following error.

$ sam local generate-event apigateway aws-proxy | sam local invoke HelloWorldFunction
Invoking not.used (provided)
Skip pulling image and use local one: amazon/aws-sam-cli-emulation-image-provided:rapid-1.13.2.

Mounting /home/***/dev/src/github.com/ichyo/aws-sam-rust-hello-world/.aws-sam/build/HelloWorldFunction as /var/task:ro,delegated inside runtime container
START RequestId: 14785d12-91f4-4630-a9ba-1d5bc88a0d86 Version: $LATEST
thread 'main' panicked at 'no entry found for key "lambda-runtime-invoked-function-arn"', /home/***/.cargo/git/checkouts/aws-lambda-rust-runtime-7c865cce90132439/13aa8f0/lambda/src/types.rs:131:35
stack backtrace:
   0: rust_begin_unwind
             at /rustc/7eac88abb2e57e752f3302f02be5f3ce3d7adfb4/library/std/src/panicking.rs:483
   1: std::panicking::begin_panic_fmt
             at /rustc/7eac88abb2e57e752f3302f02be5f3ce3d7adfb4/library/std/src/panicking.rs:437
   2: <lambda::types::Context as core::convert::TryFrom<http::header::map::HeaderMap>>::try_from
   3: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll
   4: std::thread::local::LocalKey<T>::with
   5: tokio::runtime::enter::Enter::block_on
   6: tokio::runtime::thread_pool::ThreadPool::block_on
   7: tokio::runtime::context::enter
   8: hello::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
END RequestId: 14785d12-91f4-4630-a9ba-1d5bc88a0d86
REPORT RequestId: 14785d12-91f4-4630-a9ba-1d5bc88a0d86  Init Duration: 0.16 ms  Duration: 37.97 ms      Billed Duration: 100 ms Memory Size: 128 MB     Max Memory Used: 128 MB

It seems the lambda simulation provided by AWS SAM doesn't pass several response headers including Lambda-Runtime-Invoked-Function-Arn from /runtime/invocation/next.
dumping headers at this point shows

[/home/***/dev/src/github.com/awslabs/aws-lambda-rust-runtime/lambda/src/types.rs:122] &headers = {
    "content-type": "application/json",
    "lambda-runtime-aws-request-id": "8c65869a-e73e-42fa-9195-b6887b3597f8",
    "lambda-runtime-deadline-ms": "3214327342525",
    "date": "Sun, 06 Dec 2020 06:43:19 GMT",
    "content-length": "2",
}

Steps to reproduce

1. Clone https://github.com/ichyo/aws-sam-rust-hello-world
2. (Install SAM CLI and rustup target add x86_64-unknown-linux-musl if you haven't)
3. sam build
4. sam local generate-event apigateway aws-proxy | sam local invoke HelloWorldFunction (or sam local start-api and access http://127.0.0.1:3000/)

[ichyo]

There's an issue tracking this in AWS SAM (https://github.com/aws/aws-sam-cli/issues/2456).