yarn doesn't always install dependencies

[rebornix]

• VSCode Version: 1.19-Insider
• OS Version: macOS

Node: 8.9.1
yarn: 0.16.0

Followed steps in #38481

• nvm install 8.9.1
• npm i -g yarn
• git clean -xfd
• yarn

Most of the time I got errors when installing vscode-ripgrep

[3/4] 🔗  Linking dependencies...
[4/4] 📃  Building fresh packages...
[8/16] ⠐ v8-profiler: CXX(target) Release/obj.target/profiler/src/profiler.o
[9/16] ⠐ vscode-fsevents: spawn args   '-Goutput_dir=.' ]
[10/16] ⠐ vscode-ripgrep
[4/16] ⠐ native-keymap: CXX(target) Release/obj.target/keymapping/src/keyboard_mac.o
error /Users/penlv/code/vscode/node_modules/vscode-ripgrep: Command failed.
Exit code: 1
Command: sh
Arguments: -c node ./dist/postinstall.js
Directory: /Users/penlv/code/vscode/node_modules/vscode-ripgrep
Output:
Downloading ripgrep failed: Error: Missing ./_node_modules...

I succeed installing all the packages twice, after that, I ran yarn watch or gulp watch, I got following errors

yarn watch v0.16.0
$ gulp watch --max_old_space_size=4096
[11:47:44] Node flags detected: --max_old_space_size=4096
[11:47:44] Respawned to PID: 3858
child_process.js:644
    throw err;
    ^

Error: Command failed: yarn list --json
    at checkExecSyncError (child_process.js:601:13)
    at Object.execSync (child_process.js:641:13)
    at getYarnProductionDependencies (/Users/penlv/code/vscode/build/dependencies.js:46:17)
    at Object.getProductionDependencies (/Users/penlv/code/vscode/build/dependencies.js:62:15)
    at Object.<anonymous> (/Users/penlv/code/vscode/build/gulpfile.vscode.js:38:37)
    at Module._compile (module.js:635:30)
    at Object.Module._extensions..js (module.js:646:10)
    at Module.load (module.js:554:32)
    at tryModuleLoad (module.js:497:12)
    at Function.Module._load (module.js:489:3)
    at Module.require (module.js:579:17)
    at require (internal/module.js:11:18)
    at require.sync.forEach.f (/Users/penlv/code/vscode/gulpfile.js:76:17)
    at Array.forEach (<anonymous>)
    at Object.<anonymous> (/Users/penlv/code/vscode/gulpfile.js:76:4)
    at Module._compile (module.js:635:30)

[rebornix]

vscode-ripgrep tries to check node_modules in postinstall, which doesn't exist when doing yarn install.

[rebornix]

Yarn's cache leads to this problem

• yarn cache clean
• yarn add vscode-ripgrep
• vscode-ripgrep has a folder _node_modules, it has a postscript which will remove this folder and add a new folder called bin
• if we run yarn add vscode-ripgrep again, yarn will load the module directly from cache (which has the bin folder instead of _node_modules) and try to execute postscript again.

[rebornix]

Besides, it only happens on an old version of yarn, upgrading to the latest one solves the problem.

[roblourens]

Should be fixed now

[joaomoreno]

Great job guys!