No fallback on index-url if dependency not found in local simple repository

[BenediktMaag]

I have setup a simple repository (https://packaging.python.org/en/latest/specifications/simple-repository-api/ | PEP503).

Installing a plugin from the repository by providing a extra-index-url works but when adding a dependency that is not contained in the repository uv errors instead of falling back to the index-url.

I know from #2083 that it should not continue looking if the specified verison was not found, but since no reference can be found it should continue with the primary index imo.

❯ : uv pip install cryptography --extra-index-url file:\C:\temp\simple\ -vv
0.000085s DEBUG uv uv 0.2.15
uv_requirements::specification::from_source source=cryptography
0.005378s DEBUG uv_toolchain::discovery Searching for Python interpreter in system toolchains
0.006771s DEBUG uv_toolchain::discovery Found cpython 3.12.0 at C:\temp\test_install\.venv\Scripts\python.exe (active virtual environment)
0.007211s DEBUG uv::commands::pip::install Using Python 3.12.0 environment at .venv\Scripts\python.exe
0.007755s DEBUG uv_fs Acquired lock for .venv
0.008958s DEBUG uv::commands::pip::install At least one requirement is not satisfied: cryptography
uv_client::linehaul::linehaul
0.009374s DEBUG uv_client::base_client Using request timeout of 30s
uv_resolver::flat_index::from_entries
uv_resolver::resolver::solve
uv_resolver::resolver::solve_tracked
0.012813s 0ms DEBUG uv_resolver::resolver Solving with installed Python version: 3.12.0
uv_resolver::resolver::choose_version package=root
uv_resolver::resolver::get_dependencies_forking package=root, version=0a0.dev0
uv_resolver::resolver::get_dependencies package=root, version=0a0.dev0
0.013687s 0ms DEBUG uv_resolver::resolver Adding direct dependency: cryptography*
uv_resolver::resolver::process_request request=Versions cryptography
uv_resolver::resolver::choose_version package=cryptography
uv_client::registry_client::simple_api package=cryptography
uv_resolver::resolver::process_request request=Prefetch cryptography *
error: failed to read from file C:\temp\simple\cryptography\index.html
Caused by: The system cannot find the path specified. (os error 3)

A minimal setup can be found here, github doesnt allow .7z files (maturin init compiled as 0.1.0 and 0.2.0):
https://we.tl/t-WOJyEdOD1L

[charliermarsh]

Yeah we should treat this as a 404 effectively.