Nested development depdency overrides optional flag of main package

Performing the following steps leads to a lock file where an optional main package gets marked as optional = false. This is unexpected and also seems to impeded correctly identifying package for removal during poetry install --no-dev.

Reproducer

podman run --rm -i --entrypoint bash python:3.8 <<EOF
set -xe
python -m pip install -q poetry
poetry new foobar
pushd foobar
sed -i /pytest/d pyproject.toml
poetry add --optional grpcio
poetry add --dev grpcio-tools
cat poetry.lock
poetry install --no-dev
EOF

Console Output Snippets

Lock File

Note the optional flag for grpcio package.

[[package]]
name = "grpcio"
version = "1.32.0"
description = "HTTP/2-based RPC framework"
category = "main"
optional = false
python-versions = "*"

[package.dependencies]
six = ">=1.5.2"

[package.extras]
protobuf = ["grpcio-tools (>=1.32.0)"]

[[package]]
name = "grpcio-tools"
version = "1.32.0"
description = "Protobuf code generator for gRPC"
category = "dev"
optional = false
python-versions = "*"

[package.dependencies]
grpcio = ">=1.32.0"
protobuf = ">=3.5.0.post1,<4.0dev"

[[package]]
name = "protobuf"
version = "3.13.0"
description = "Protocol Buffers"
category = "dev"
optional = false
python-versions = "*"

[package.dependencies]
six = ">=1.9"

[[package]]
name = "six"
version = "1.15.0"
description = "Python 2 and 3 compatibility utilities"
category = "main"
optional = false
python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*"

[metadata]
lock-version = "1.1"
python-versions = "^3.8"
content-hash = "2a7da8afdc04c79ebc47003e6a50e1da2e57dd605b79e754dece9fd74042c14e"

[metadata.files]
...

Output for install --no-dev

Installing dependencies from lock file

Package operations: 0 installs, 0 updates, 2 removals

  • Removing grpcio-tools (1.32.0)
  • Removing protobuf (3.13.0)

Installing the current project: foobar (0.1.0)

You'll note that `grpcio was not removed.

Start by running the provided Podman reproducer and compare pyproject.toml with poetry.lock after adding optional grpcio and dev grpcio-tools. Inspect the dependency-locking and install paths involved in marking grpcio optional and selecting removals for poetry install --no-dev. Done means the lock file preserves grpcio's optional status and the command removes it when appropriate.