uv 0.8.12 panics with internal error: entered unreachable code: Installed distribution could not be found in site-packages

[alex]

Summary

Full logs here: https://github.com/pyca/cryptography/actions/runs/17084993363/job/48447256454 (from pyca/cryptography#13322)

Relevant bit:

DEBUG Build info mismatch for cryptography-vectors: Url(InstalledDirectUrlDist { name: PackageName("cryptography-vectors"), version: "46.0.0.dev1", direct_url: LocalDirectory { url: "file:///home/runner/work/cryptography/cryptography/vectors", dir_info: DirInfo { editable: Some(true) }, subdirectory: None }, url: DisplaySafeUrl { scheme: "file", cannot_be_a_base: false, username: "", password: None, host: None, port: None, path: "/home/runner/work/cryptography/cryptography/vectors", query: None, fragment: None }, editable: true, path: "/home/runner/work/cryptography/cryptography/.nox/tests-rust-debug/lib/python3.13/site-packages/cryptography_vectors-46.0.0.dev1.dist-info", cache_info: Some(CacheInfo { timestamp: Some(Timestamp(SystemTime { tv_sec: 1755649240, tv_nsec: 464897504 })), commit: None, tags: None, env: {}, directories: {"src": None} }), build_info: Some(BuildInfo { config_settings: ConfigSettings({}), extra_build_requires: [], extra_build_variables: {} }) })
DEBUG Requirement installed, but not fresh: cryptography-vectors==46.0.0.dev1 (from file:///home/runner/work/cryptography/cryptography/vectors)

thread 'main2' panicked at crates/uv-installer/src/plan.rs:159:17:
internal error: entered unreachable code: Installed distribution could not be found in site-packages: cryptography-vectors==46.0.0.dev1 (from file:///home/runner/work/cryptography/cryptography/vectors)
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

The invocation is https://github.com/pyca/cryptography/blob/main/noxfile.py#L73-L78

Platform

Ubuntu 24.04

Version

0.8.12

Python version

3.13

[woodruffw]

Just doing some triage:

Failure point is here:

uv/crates/uv-installer/src/plan.rs

Lines 158 to 160 in 249154e

	let ResolvedDist::Installable { dist, .. } = dist else {
	unreachable!("Installed distribution could not be found in site-packages: {dist}");
	};

Most recent proximate change is #15289

Edit: This looks like the assumption that changed:

uv/crates/uv-installer/src/plan.rs

Lines 92 to 97 in 59f4598

	// TODO(charlie): There are a few assumptions here that are hard to spot:
	//
	// 1. Apparently, we never return direct URL distributions as [`ResolvedDist::Installed`].
	// If you trace the resolver, we only ever return [`ResolvedDist::Installed`] if you go
	// through the [`CandidateSelector`], and we only go through the [`CandidateSelector`]
	// for registry distributions.

[zanieb]

Thank you for the report! (and for the triage William!)

cc @charliermarsh

[charliermarsh]

I’ll take a look today, thanks.

[charliermarsh]

Thanks, I was able to reproduce this. I understand what's going on -- I think it's actually the same "odd" panic that showed up in #15234. It's actually kind of hard to fix, I'll look for a simple patch for now to unblock.

[charliermarsh]

Ok, #15389 should restore the existing behavior in these cases.

[charliermarsh]

As an aside, in that noxfile, you might want to use --config-settings-package cryptography:build-args=--profile=dev instead, to scope the configuration to cryptography. In the future, adding --config-settings=build-args=--profile=dev may cause us to rebuild other already-installed source distributions with those new settings, since they aren't scoped to a specific package.

[alex]

Cool, thanks, will do!