Missing renames for stable channel

Problem
Cannot use rustup component add rls --toolchain stable, but rustup component add rls-preview --toolchain stable works. This appears to be because the renames table in ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/multirust-channel-manifest.toml is missing. Instead there is a rename table declared at the end of the file with no entries in it (gist with full content).

I installed the 1.34.0 toolchain as well to check, and that appears to be working correctly (gist of the manifest).

This is a laptop that has been using rustup for a long time, checking the date of the ~/.multirust symlink that is from 2016-12-21, so likely rustup v1.0; but at the same time I will have been updating stable very rarely as I mostly use nightly.

Notes

Output of rustup --version: rustup 1.18.0 (8603e2c56 2019-04-22)
Output of rustc +stable --version: rustc 1.34.0 (91856ed52 2019-04-10)
Output of rustup show:

Default host: x86_64-unknown-linux-gnu

installed toolchains
--------------------

stable-x86_64-unknown-linux-gnu
nightly-2017-01-26-x86_64-unknown-linux-gnu
nightly-2018-02-27-x86_64-unknown-linux-gnu
nightly-2018-02-28-x86_64-unknown-linux-gnu
nightly-2018-03-18-x86_64-unknown-linux-gnu
nightly-2018-04-02-x86_64-unknown-linux-gnu
nightly-2018-04-06-x86_64-unknown-linux-gnu
nightly-2018-04-16-x86_64-unknown-linux-gnu
nightly-2018-09-17-x86_64-unknown-linux-gnu
nightly-2018-10-14-x86_64-unknown-linux-gnu
nightly-2019-01-11-x86_64-unknown-linux-gnu
nightly-2019-04-04-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu (default)
unpin
1.0.0-x86_64-unknown-linux-gnu
1.7.0-x86_64-unknown-linux-gnu
1.10.0-x86_64-unknown-linux-gnu
1.15.0-x86_64-unknown-linux-gnu
1.20.0-x86_64-unknown-linux-gnu

installed targets for active toolchain
--------------------------------------

arm-unknown-linux-gnueabi
thumbv6m-none-eabi
wasm32-unknown-unknown
x86_64-unknown-linux-gnu

active toolchain
----------------

nightly-x86_64-unknown-linux-gnu (default)
rustc 1.36.0-nightly (e305df184 2019-04-24)