Always perform version-negotiation

If a client is initialized without a specific
version set, version negotiation would not be
functional.

This patch changes the behavior to always
perform version negotation (if called), in
which case the "current" (maximum supported
API version) is used as a default.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: 5975dc4b4b8a6fa2e0edd1f1b113e7f66dad732b
Component: engine

components/engine/client/client.go

@@ -260,8 +260,13 @@ func (cli *Client) NegotiateAPIVersionPing(p types.Ping) {
 		p.APIVersion = "1.24"
 	}
 
-	// if server version is lower than the current cli, downgrade
-	if versions.LessThan(p.APIVersion, cli.ClientVersion()) {
+	// if the client is not initialized with a version, start with the latest supported version
+	if cli.version == "" {
+		cli.version = api.DefaultVersion
+	}
+
+	// if server version is lower than the maximum version supported by the Client, downgrade
+	if versions.LessThan(p.APIVersion, api.DefaultVersion) {
 		cli.version = p.APIVersion
 	}
 }