Merge pull request #15964 from duglin/APIVersion

Add a DOCKER_API_VERSION env var
Upstream-commit: 905f3336b2715b3960b5ff4f860db387797d9adf
Component: engine

components/engine/api/server/router/system/system_routes.go

@@ -37,7 +37,7 @@ func (s *systemRouter) getInfo(ctx context.Context, w http.ResponseWriter, r *ht
 
 func (s *systemRouter) getVersion(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
 	info := s.backend.SystemVersion()
-	info.APIVersion = api.Version
+	info.APIVersion = api.DefaultVersion
 
 	return httputils.WriteJSON(w, http.StatusOK, info)
 }