Post-f8c0d92a22bad004cb9cbb4db704495527521c42, BUILDKIT_REPO doesn't
really do what it claims to. Instead, don't allow overloading since the
import path for BuildKit is always the same, and make clear the
provenance of values when generating the final variable definitions.
We also better document the script, and follow some best practices for
both POSIX sh and Bash.
Signed-off-by: Bjorn Neergaard <bjorn.neergaard@docker.com>
To make the local build environment more correct and consistent, we
should never leave an uncommitted go.mod in the tree; however, we need a
go.mod for certain commands to work properly. Use a wrapper script to
create and destroy the go.mod as needed instead of potentially changing
tooling behavior by leaving it.
If a go.mod already exists, this script will warn and call the wrapped
command with GO111MODULE=on.
Signed-off-by: Bjorn Neergaard <bneergaard@mirantis.com>