As noted by #30083, the new strict checking of mediatypes misses some
cases where earlier bugs caused nonstandard mediatypes to be stored in
manifests. Two of the known cases are text/html and application/json,
which were returned by certain registries and stored by earlier versions
of Docker. Add special cases for text/html and application/json.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
(cherry picked from commit a215e15cb1)
Signed-off-by: Victor Vieux <vieux@docker.com>