feat(pipelines/depot): Skip build steps if their out paths exist r/2786

Skip build steps if they have already been built, reducing pipelines
to the things that actually changed between builds. On canon all
targets are always built (we require this for anchoring).

Note that this is not perfect, garbage collection and competing
pipelines may affect each other.

Also note that we have some impure targets that change on every
commit.

Change-Id: Ic6bae3b6c8e1e7fd2116ec252f5089f471854ab6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3427
Tested-by: BuildkiteCI
Reviewed-by: sterni <sternenseemann@systemli.org>
Reviewed-by: grfn <grfn@gws.fyi>

0 files changed, 0 insertions, 0 deletions