`ng-packages-installer` can be used to replace Angular packages with
locally built ones (from `dist/packages-dist/`) along with their peer
dependencies.
Previously, in order to achieve this, `yarn install` was called with the
`--no-lockfile` option, which resulted in installing the latest versions
of all dependencies (including transitive ones) permitted by the
corresponding version ranges in `package.json` files. As a result, newly
released versions would be picked, resulting in unexpected,
non-deterministic breakages in CI.
This commit calls `yarn install` with the `--pure-lockfile` option
instead. As a result, only the Angular packages (for which the locally
built ones are used) and their peer dependencies are unpinned; the
pinned versions from `yarn.lock` are used for all other (direct and
transitive) dependencies.
While this does not eliminate non-determinism across builds, it
significantly reduces it.
PR Close#28510
George Kalpakas
Peter Bacon Darwin