Failure publishing some crates due to missing dep versions

[calebcartwright]

There's been some intermittent publish failures over the last few weeks that's resulted in a couple missing crate versions, most recently with rustc_parse. I'm hoping the issue is just timing with dependency relationships between these crates, and the new dependent version not quite hitting the index before the consuming crate versions are published.

publishing rustc_fs_util 663.0.0
    Updating crates.io index
   Packaging rustc-ap-rustc_fs_util v663.0.0 (/private/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/foo.bixavKjKmtxA/rust-ccac43b86b559e01fa71179af1a838ab94559c75/src/librustc_fs_util)
   Uploading rustc-ap-rustc_fs_util v663.0.0 (/private/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/foo.bixavKjKmtxA/rust-ccac43b86b559e01fa71179af1a838ab94559c75/src/librustc_fs_util)
publishing rustc_session 663.0.0
    Updating crates.io index
   Packaging rustc-ap-rustc_session v663.0.0 (/private/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/foo.bixavKjKmtxA/rust-ccac43b86b559e01fa71179af1a838ab94559c75/src/librustc_session)
   Uploading rustc-ap-rustc_session v663.0.0 (/private/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/foo.bixavKjKmtxA/rust-ccac43b86b559e01fa71179af1a838ab94559c75/src/librustc_session)
publishing rustc_parse 663.0.0
    Updating crates.io index
error: failed to select a version for the requirement `rustc-ap-rustc_session = "^663.0.0"`
  candidate versions found which didn't match: 662.0.0, 660.0.0, 659.0.0, ...
  location searched: crates.io index
required by package `rustc-ap-rustc_parse v663.0.0 (/private/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/foo.bixavKjKmtxA/rust-ccac43b86b559e01fa71179af1a838ab94559c75/src/librustc_parse)`
thread 'main' panicked at 'assertion failed: result.success()', src/main.rs:380:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
##[error]Process completed with exit code 101.