Building on nix

I am using this script to build rust using the mozilla rust overlay for nix.

https://github.com/brettgilio/guix-system/blob/master/manifests/nightly-rust-manifest.nix

This worked fine for awhile, however about a week or two ago it started failing with this error.

error[E0277]: the trait bound `std::borrow::Cow<'_, str>: std::convert::From<core::str::EscapeDefault<'_>>` is not satisfied
   --> /build/rls-1.31.7-vendor/rustc-ap-graphviz/lib.rs:551:44
    |
551 |                     (&*s).escape_default().into()
    |                                            ^^^^ the trait `std::convert::From<core::str::EscapeDefault<'_>>` is not implemented for `std::borrow::Cow<'_, str>`
    |
    = help: the following implementations were found:
              <std::borrow::Cow<'a, [T]> as std::convert::From<&'a [T]>>
              <std::borrow::Cow<'a, [T]> as std::convert::From<&'a std::vec::Vec<T>>>
              <std::borrow::Cow<'a, [T]> as std::convert::From<std::vec::Vec<T>>>
              <std::borrow::Cow<'a, std::ffi::CStr> as std::convert::From<&'a std::ffi::CStr>>
            and 11 others
    = note: required because of the requirements on the impl of `std::convert::Into<std::borrow::Cow<'_, str>>` for `core::str::EscapeDefault<'_>`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.
error: Could not compile `rustc-ap-graphviz`.
warning: build failed, waiting for other jobs to finish...
error: build failed
builder for '/nix/store/vfw5pdqckqm6024kmvqm65jvsc9mfkxy-rls-1.31.7.drv' failed with exit code 101
error: build of '/nix/store/94ir2l1ac2yfcfc1fph6w3x4ghp5rah6-rust-analysis-1.36.0-nightly-2019-04-29-00859e3e6.drv', '/nix/store/a77wjq236g9h01hbd63ij5d9khgqbm5v-rust-src-1.36.0-nightly-2019-04-29-00859e3e6.drv', '/nix/store/vfw5pdqckqm6024kmvqm65jvsc9mfkxy-rls-1.31.7.drv', '/nix/store/w8pqky54afqcz5kxx0j0zsq80jyv4950-rust-1.36.0-nightly-2019-04-29-00859e3e6.drv' failed

I thought maybe it was an upstream issue, but I am lost with how long this issue has been persisting. Any suggestions?

[tesuji]

Current RLS version is 1.36.0. You should try to update it.
This is error because str::escape has been stabilized in #58051
(and bug fixed in https://github.com/rust-lang/rust/pull/58051/files#diff-5df012de31a1bde391411c75eaa4fbfeR540)