vscode-extensions.matklad.rust-analyzer broken on master

[poscat0x04]

Describe the bug
the vscode extension "matklad.rust-analyzer" cannot be built.

> nix-build -A vscode-extensions.matklad.rust-analyzer
these derivations will be built:
  /nix/store/s6rhi5dqjk3r0ihkf006zmjcxz9ar8hx-vscode-extension-rust-analyzer-unstable-2020-04-20.drv
building '/nix/store/s6rhi5dqjk3r0ihkf006zmjcxz9ar8hx-vscode-extension-rust-analyzer-unstable-2020-04-20.drv'...
unpacking sources
unpacking source archive /nix/store/9lc7vfqrk9fxnfmc8g7vw85jzkdfs0z8-node_rust-analyzer-0.4.0-dev-vsix/rust-analyzer.zip
source root is extension
setting SOURCE_DATE_EPOCH to timestamp 1590867416 of file extension/README.md
patching sources
configuring
building
installing
post-installation fixup
patching script interpreter paths in /nix/store/anqxphns351brlj0zc8x38g6q3fclm59-vscode-extension-rust-analyzer-unstable-2020-04-20
checking for references to /build/ in /nix/store/anqxphns351brlj0zc8x38g6q3fclm59-vscode-extension-rust-analyzer-unstable-2020-04-20...
/nix/store/b0jz23gnnyjrr72rz36xkc3wr36isky6-stdenv-linux/setup: line 82: /nix/store/anqxphns351brlj0zc8x38g6q3fclm59-vscode-extension-rust-analyzer-unstable-2020-04-20/matklad.rust-analyzer/package.json.new: No such file or directory
builder for '/nix/store/s6rhi5dqjk3r0ihkf006zmjcxz9ar8hx-vscode-extension-rust-analyzer-unstable-2020-04-20.drv' failed with exit code 1
error: build of '/nix/store/s6rhi5dqjk3r0ihkf006zmjcxz9ar8hx-vscode-extension-rust-analyzer-unstable-2020-04-20.drv' failed

Notify maintainers

cc @oxalica

Metadata
Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

• system: "x86_64-linux"
• host os: Linux 5.4.30, NixOS, 20.03beta1155.29eddfc36d7 (Markhor)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.2
• channels(poscat): ""
• channels(root): "nixos-20.03beta1155.29eddfc36d7, home-manager"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
# a list of nixos modules affected by the problem
module: