Cleanup all the mutate + defer revert of b.runConfig in the builder

Instead of mutating and reverting, just create a copy and pass the copy
around.

Add a unit test for builder dispatcher.run

Fix two test failures

Fix image history by adding a CreatedBy to commit options. Previously the
createdBy field was being created by modifying a reference to the runConfig that
was held from when the container was created.

Fix a test that expected a trailing slash. Previously the runConfig was being
modified by container create. Now that we're creating a copy of runConfig
instead of sharing a reference the runConfig retains the trailing slash.

Signed-off-by: Daniel Nephin <dnephin@docker.com>
Upstream-commit: 9f738cc574d50d0a2accdf6f6deb30405c24a80c
Component: engine

components/engine/api/types/backend/backend.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/docker/docker/api/types"
+	"github.com/docker/docker/api/types/container"
 )
 
 // ContainerAttachConfig holds the streams to use when connecting to a container to view logs.
@@ -97,4 +98,7 @@ type ExecProcessConfig struct {
 type ContainerCommitConfig struct {
 	types.ContainerCommitConfig
 	Changes []string
+	// TODO: ContainerConfig is only used by the dockerfile Builder, so remove it
+	// once the Builder has been updated to use a different interface
+	ContainerConfig *container.Config
 }