To enforce immutability of the `DefaultBackoffConfig`, we've made it a
concrete value. While fields can still be set directly on the value,
taking a copy will not incidentally pull a reference to the variable.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
Because most of the fields on `BackoffConfig` are unexported, correctly
using the config requires copying from the default. This sets the
defaults appropriately and falls back to a default if MaxDelay is
negative or zero.
Tests are added to ensure that the backoff is set correctly in common
use cases.
Signedroff-by: Stephen J Day <stephen.day@docker.com>
Signed-off-by: Stephen J Day <stephen.day@docker.com>
