keep empty environment variables as those must be UNSET in container #654
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environment
FOO
with no value nor equal sign means "propagate value from user's environment, or unset variable"So, as we resolve environment, empty value with no matching entry in user's environment MUST not result into removing entry from service definition.
Build args do not follow this rule.
--build-arg FOO
will propagate user's environment value, but if not set build arg will keep using value set by Dockerfilefixes docker/compose#11962
supersede #634
see docker/compose#11965