reproduce poetry export issue with explicit source

pyproject.toml

[tool.poetry]
name = "poetry-export-issue-2023-05-23"
version = "0.1.0"
description = ""
authors = ["XXX <[email protected]>"]
readme = "README.md"
packages = [{include = "poetry_export_issue_2023_05_23"}]

[tool.poetry.dependencies]
python = "^3.10"
black = {version = "^23.3.0", source = "foo"}

[[tool.poetry.source]]
name = "foo"
url = "http://localhost:8080/"
priority = "explicit"

[[tool.poetry.source]]
name = "PyPI"
priority = "primary"

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