Build: resolve copyFrom references earlier
Build: resolve copyFrom references earlier

Resolve a possible copyFrom argument to a location before we possibly
call into the imagebuilder Run() method that might call back to our
Copy() method.

Signed-off-by: Nalin Dahyabhai <nalin@redhat.com>

Closes: #1409
Approved by: TomSweeneyRedHat

TomSweeneyRedHat/buildah,nalind/buildah-1,nalind/buildah,projectatomic/buildah,TomSweeneyRedHat/buildah,nalind/buildah-1,projectatomic/buildah,nalind/buildah-1,projectatomic/buildah,nalind/buildah,TomSweeneyRedHat/buildah,rhatdan/buildah,rhatdan/buildah,rhatdan/buildah