Running pip-tools compile on multiple sources fails with --all-extras

[dragly]

Running pip-tools compile with --all-extras on multiple sources containing extras always fails with the following error:

Error: Invalid value: --extra has no effect when used with --all-extras

Environment Versions

1. Linux
2. Python version: python 3.10.8
3. pip version: pip 22.2.2
4. pip-tools version: pip-compile, version 7.3.1.dev21

Steps to replicate

1. Create two small projects with pyproject.toml containing

[project]
name = "package-a"
version = "0.1.0"

[project.optional-dependencies]
test = []

2. Run python -m piptools compile --all-extras package-a/pyproject.toml package-b/pyproject.toml

Expected result

A requirements.txt file for the combined projects including all extras should be generated.

Actual result

Error: Invalid value: --extra has no effect when used with --all-extras