regression in README parsing

[Mark-Simulacrum]

Update

This has been fixed and the next nightly (2020-06-13) should contain the fix assuming rust-lang/rust#73266 lands. Nightly releases are usually published around 00:30 to 01:00 UTC.

Original issue

As of rust-lang/rust#73198 (presumably #8277), Cargo fails to find README in some published crates, leading to failures at build time:

error: failed to download `encoding-index-japanese v1.20141219.5`

Caused by:
  unable to get packages from source

Caused by:
  failed to parse manifest at `/home/mark/.cargo/registry/src/github.tiyicn.workers.dev-1ecc6299db9ec823/encoding-index-japanese-1.20141219.5/Cargo.toml`

Caused by:
  readme file with name '../../../README.md' was not found

Reproduction:

$ cp -pri ~/.cargo/registry/src/github.tiyicn.workers.dev-*/encoding-index-japanese-1.20141219.5 ./
$ cd encoding-index-japanese-1.20141219.5
$ cargo read-manifest
error: failed to parse manifest at `/tmp/tmp.8aqcVQDq2K/encoding-index-japanese-1.20141219.5/Cargo.toml`

Caused by:
  readme file with name '../../../README.md' was not found

Note that this hasn't hit nightly yet but it's likely too late to revert it before it does. This is breaking rustc-perf at least (and probably lots of other places that depend on crates published without READMEs included).

[ehuss]

I'll take a look.

[ehuss]

Just going to reopen until the next nightly is published.

[kitsuneninetails]

Yup. We saw this in our CI/CD systems this morning. Caused quite a stir and a ton of lost time debugging until we realized it was the nightly version. Unfortunate this crept in. Are the no tests for this regression in place? Should we add them?