Poetry config demonstrating inconsistent behaviour between poetry install and pip install

pyproject.toml

[tool.poetry]
name = "package-a"
version = "0.1.0"
description = ""
authors = ["Omegastick <isaac@poulton.dev>"]
readme = "README.md"
packages = [{include = "package_a"}]

[tool.poetry.dependencies]
python = "^3.9"
package-b = [
    {version = "^0.1.0", markers = "extra == 'internal'", optional = true},
    {path = "../package_b", develop = true, markers = "extra == 'local'", optional = true},
]

[tool.poetry.extras]
internal = ["package-b"]
local = ["package-b"]

[build-system]
requires = ["poetry-core"]
build-backend = "poetry.core.masonry.api"