cargo-metadata always resolves features at the workspace level

Problem
cargo-metadata appears to always resolve features at the "workspace" level, rather than for root crate. This means that cargo metadata will report features as enabled that aren't actually when cargo build is run in the same directory.

Steps

1. Clone https://github.com/sfackler/rust-postgres
2. Run cargo metadata --format-version 1 --manifest-path postgres-derive/Cargo.toml | jq '.resolve.nodes|.[]|select(.id|test("postgres-types"))'.
3. Note that the entry for postgres-types has the derive and postgres-derive features enabled even though they are off by default for that crate. The postgres-derive-test crate in the same workspace enables that feature, which I assume is where that's coming from:

{
  "id": "postgres-types 0.1.0 (path+file:///home/sfackler/code/rust-postgres/postgres-types)",
  "dependencies": [
    "bytes 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)",
    "fallible-iterator 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
    "postgres-derive 0.4.0 (path+file:///home/sfackler/code/rust-postgres/postgres-derive)",
    "postgres-protocol 0.5.0 (path+file:///home/sfackler/code/rust-postgres/postgres-protocol)"
  ],
  "deps": [
    {
      "name": "bytes",
      "pkg": "bytes 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)",
      "dep_kinds": [
        {
          "kind": null,
          "target": null
        },
        {
          "kind": null,
          "target": null
        }
      ]
    },
    {
      "name": "fallible_iterator",
      "pkg": "fallible-iterator 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
      "dep_kinds": [
        {
          "kind": null,
          "target": null
        },
        {
          "kind": null,
          "target": null
        }
      ]
    },
    {
      "name": "postgres_derive",
      "pkg": "postgres-derive 0.4.0 (path+file:///home/sfackler/code/rust-postgres/postgres-derive)",
      "dep_kinds": [
        {
          "kind": null,
          "target": null
        }
      ]
    },
    {
      "name": "postgres_protocol",
      "pkg": "postgres-protocol 0.5.0 (path+file:///home/sfackler/code/rust-postgres/postgres-protocol)",
      "dep_kinds": [
        {
          "kind": null,
          "target": null
        },
        {
          "kind": null,
          "target": null
        }
      ]
    }
  ],
  "features": [
    "derive",
    "postgres-derive"
  ]
}

Possible Solution(s)
cargo metadata should respect the root crate when resolving the crate graph.

Notes

Output of cargo version: cargo 1.41.0-nightly (19a0de242 2019-12-12)

Reproduce the behavior in the rust-postgres workspace with the documented cargo metadata command, then compare its feature resolution with cargo build for postgres-derive/Cargo.toml. Trace Cargo's workspace and root-crate metadata resolution entry points; done means metadata reports only features enabled for the selected root crate.