tests.unit.config: Make sure volume order is preserved.
tests.unit.config: Make sure volume order is preserved.

Signed-off-by: Antony MECHIN <65787f2a9ff9be37bf8e16418237b0da956f51cf@docker.com>

vdemeester/compose,thaJeztah/compose,thaJeztah/compose,vdemeester/compose