Since the Docker-Distribution-API-Version header value may contain multiple
space delimited versions as well as many instances of the header key, the
header value is now split on whitespace characters to iterate over all versions
that may be listed in one instance of the header.
Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)
Upstream-commit: 58c142bcfa2b9edce7efe72d393e9f90b9df9927
Component: engine