Psych::Nodes::Scalar::LITERAL ignored in encode_with?

まず、カスタムクラスの encode_with メソッドを使い、coder.scalar、coder.tag、および Psych::Nodes::Scalar::LITERAL を設定して、短い YAML 出力と長い YAML 出力を再現します。Psych がスカラーの長さとエスケープされた改行をどのように扱うかを比較し、その後、文書化された動作と生成された出力のどちらが誤っているのかを判断します。完了条件は、原因が説明され、焦点を絞った回帰テストまたはドキュメント変更が特定されていることです。

This could just me, but I really lost and I don't understand why this works this way.

I have a big YAML with various string values. One of them is an encoded file content which is nice for machine consumption but I want to show that as a literal for human beings.

I created a separate class for those values and I added an encode_with method.

                def encode_with( coder )
                        coder.scalar = @str                                                                                                                                 
                        coder.tag = "!file_content"
                        coder.style = Psych::Nodes::Scalar::LITERAL
                end

When the value is short then it works as expected but if it is longer then output is still quoted.

---
hello: world
short: !file_content |
  TEST_DOCKER_IMAGE="foobar/image:1.2.3-r4"
long: !file_content "!\n! %[CONN_NAME]\n!\nneighbor %[REMOTE_ADDRESS] remote-as %[REMOTE_ASN]\nneighbor
  %[REMOTE_ADDRESS] description %[CONN_NAME]\naddress-family ipv6\n\tneighbor %[REMOTE_ADDRESS]
  activate\n\tneighbor %[REMOTE_ADDRESS] soft-reconfiguration inbound\n\tneighbor
  %[REMOTE_ADDRESS] prefix-list ipv6_ranges in\n\tneighbor %[REMOTE_ADDRESS] prefix-list
  ipv6_ranges out\n\tneighbor %[REMOTE_ADDRESS] route-map add_extra_hop in\n\tneighbor
  %[REMOTE_ADDRESS] route-map no_advertise_self out\nexit-address-family\n"

The documentation is quite scarce about this topic. Do I miss something? Or is this a bug in Psych?