message: ci: keep cache key fallback in a var
  This way it's right next to the original key and it's easier to keep them in sync.
  PR Close
diff: @@ -18,14 +18,17 @@ version: 2.1
  # cache changes. For example:
  # 1) yarn lock file changes --> cached "node_modules" are different.
  # 2) bazel repository definitions change --> cached bazel repositories are different.
  -# **NOTE 1 **: If you change the cache key prefix, also sync the restore_cache fallback to match.
  +# Windows needs its own cache key because binaries in node_modules are different.
  +# **NOTE 1 **: If you change the cache key prefix, also sync the cache_key_fallback to match.
  # **NOTE 2 **: Keep the static part of the cache key as prefix to enable correct fallbacks.
  # See https://circleci.com/docs/2.0/caching/#restoring-cache for how prefixes work in CircleCI.
  var_3: &cache_key v3-angular-node-10.16-{{ checksum "yarn.lock" }}-{{ checksum "WORKSPACE" }}-{{ checksum "packages/bazel/package.bzl" }}-{{ checksum "aio/yarn.lock" }}
  +var_4: &cache_key_fallback v3-angular-node-10.16-
  var_3_win: &cache_key_win v4-angular-win-node-12.0-{{ checksum "yarn.lock" }}-{{ checksum "WORKSPACE" }}-{{ checksum "packages/bazel/package.bzl" }}-{{ checksum "aio/yarn.lock" }}
  +var_4_win: &cache_key_win_fallback v4-angular-win-node-12.0-
  # Initializes the CI environment by setting up common environment variables.
  -var_4: &init_environment
  +var_5: &init_environment
  run:
  name: Initializing environment (setting up variables, overwriting Yarn)
  # Overwrite the yarn installed in the docker container with our own version.
  @@ -50,7 +53,7 @@ var_4_win: &init_environment_win
  name: Setup windows node environment
  command: ./.circleci/windows-env.ps1
  -var_5: &setup_bazel_remote_execution
  +var_6: &setup_bazel_remote_execution
  run:
  name: "Setup bazel RBE remote execution"
  command: |
  @@ -112,14 +115,12 @@ var_10: &restore_cache
  restore_cache:
  keys:
  - *cache_key
  - # This fallback should be the cache_key without variables.
  - - v3-angular-node-10.16-
  + - *cache_key_fallback
  var_10_win: &restore_cache_win
  restore_cache:
  keys:
  - *cache_key_win
  - # This fallback should be the cache_key without variables.
  - - v4-angular-win-node-12.0-
  + - *cache_key_fallback_win
  # Branch filter that can be specified for jobs that should only run on publish branches
  # (e.g. master or the patch branch)
  