Docker Engine 18.09 (API v1.39) introduced a Warnings field in the into response.
This enhancement was not gated by API version (see [moby/moby@a3d4238]), and
will be returned by Docker Engine 18.09 and up, regardless of the API version
chosen.
Likewise, the client-side code was written to prefer warnings returned by
the daemon, but to fall back on client-side detection of missing features
based on information in the Info response (see [docker/cli@3c27ce2]).
Thse warnings are purely informational, and given that Docker Engine versions
before 18.09 have reached EOL 6 Years ago, and any current version of the
Engine now returns the Warnings, it should be safe to remove the client-side
fall back logic.
This patch removes the client-side fall back code for warnings that was
added in 3c27ce21c9.
[moby/moby@a3d4238]: a3d4238b9c
[docker/cli@3c27ce2]: 3c27ce21c9
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>