sourceresolver: Always try to read chunk morph files from definitions

This fixes the 'Morph ignores the chunk morph file I added to
definitions' regression introduced in the recent build-graph speedups
branch.

The new 'detected-chunk-buildsystems' cache associates a (chunk repo,
chunk ref) pair with the auto-detected build system. When calculating
the build graph, if the is an auto-detected build system known already,
that will be used instead of looking for a chunk morphology.

There's a flaw here: if the user added or changed the chunk morphology
in the definitions repo, the *chunk* ref won't necessarily have changed
-- so Morph will ignore the user's changes, if it had already cached an
autodetected buildsystem for that repo/ref pair.

This doesn't cost much in terms of speed because we're just reading a
file from disk. We can still avoid looking in the chunk repo for a chunk
morph, because the chunk ref would be different if something had changed
in the chunk repo.

0 files changed, 0 insertions, 0 deletions