I think the intention was to use "" for bits with substititions and '' for bits
without, but that makes it hard to read and the bits in '' are safe in the ""
context anyway.
Running:
./scripts/update-component-sha.sh --image linuxkit/runc 100d0d046c
Still DTRT and updates runc to that (bogus) sha.
Signed-off-by: Ian Campbell <ijc@docker.com>