cache: Yarn restores cache, but does not install from it

Hey team!

First, awesome job on this feature, it will immensely help our CI speed for our JavaScript projects, kudos!

I’ve been running on the “over the limit” error for a yarn project with workspaces enabled:

Post job cleanup.
/bin/tar -cz -f /home/runner/work/_temp/3c08f6f0-f11f-4d8f-bed5-d491e7d8d443/cache.tgz -C /home/runner/.cache/yarn .
##[warning]Cache size of 231440535 bytes is over the 200MB limit, not saving cache.

But when I run the same tar command locally, I get a 100.3 MB bundle. Is there anything I’m missing here?

Here’s my workflow:

name: Test
on:
  push:
    branches:
      - '**'
    tags:
      - '!**'
jobs:
  test:
    name: Test, lint, typecheck and build
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@master
      - name: Dump GitHub context
        env:
          GITHUB_CONTEXT: ${{ toJson(github) }}
        run: echo "$GITHUB_CONTEXT"
      - name: Use Node.js 10.16.0
        uses: actions/setup-node@v1
        with:
          node-version: 10.16.0
      - name: Cache yarn node_modules
        uses: actions/cache@v1
        with:
          path: ~/.cache/yarn
          key: ${{ runner.OS }}-yarn-${{ hashFiles('**/yarn.lock') }}
          restore-keys: |
            ${{ runner.os }}-yarn-
      - name: Install
        run: yarn install --frozen-lockfile
        # ...

Thanks a lot!