Fallback errors are not an error, but an
informational message.
This changes those errors to be logged
as "Info" instead of "Error".
After this patch, debug logs look like this;
DEBU[0050] Calling GET /_ping
DEBU[0050] Calling POST /v1.27/images/create?fromImage=localhost%3A5000%2Ffoo&tag=latest
DEBU[0050] Trying to pull localhost:5000/foo from https://localhost:5000 v2
WARN[0050] Error getting v2 registry: Get https://localhost:5000/v2/: http: server gave HTTP response to HTTPS client
INFO[0050] Attempting next endpoint for pull after error: Get https://localhost:5000/v2/: http: server gave HTTP response to HTTPS client
DEBU[0050] Trying to pull localhost:5000/foo from http://localhost:5000 v2
INFO[0050] Attempting next endpoint for pull after error: manifest unknown: manifest unknown
DEBU[0050] Trying to pull localhost:5000/foo from https://localhost:5000 v1
DEBU[0050] attempting v1 ping for registry endpoint https://localhost:5000/v1/
DEBU[0050] Fallback from error: Get https://localhost:5000/v1/_ping: http: server gave HTTP response to HTTPS client
INFO[0050] Attempting next endpoint for pull after error: Get https://localhost:5000/v1/_ping: http: server gave HTTP response to HTTPS client
DEBU[0050] Trying to pull localhost:5000/foo from http://localhost:5000 v1
DEBU[0050] [registry] Calling GET http://localhost:5000/v1/repositories/foo/images
ERRO[0050] Not continuing with pull after error: Error: image foo:latest not found
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>