- When pulling warmup images for concurrent tests, save
the images to a cache directory under the application root.
- Serial tests that aren't testing pull can save time by restoring
a cached warmup image.
- Closes#2001.
- Handle "container exists" error gracefully instead
of failing, when trying to start the buildkit container.
- Move build tests to parallel suites, while the builder
lifecycle tests remain serial. Parallel builds don't
use the fixture lock that deletes and restarts the
builder and runs a build block in isolation.
J Logan