Patch sdcadm to know why an instance hasn't got a known associated server

sdcadm.diff

diff --git a/lib/sdcadm.js b/lib/sdcadm.js
index 156d743..e797d28 100644
--- a/lib/sdcadm.js
+++ b/lib/sdcadm.js
@@ -2307,7 +2307,11 @@ SdcAdm.prototype.genUpdatePlan = function genUpdatePlan(options, cb) {
             function checkMinPlatform(ins, chg) {
                 if (ins.service === chg.service.name) {
                     server = serverFromUuidOrHostname[ins.server];
+                    if (!server) {
+                        progress('Unknown server for instance: ');
+                        console.log(util.inspect(ins, false, 8, true));
+                    }
-                    if (server.current_platform <
+                    if (server && server.current_platform <
                         self.config.vmMinPlatform) {
                         errs.push(new errors.UpdateError(format(
                             'insufficient platform for service "%s" ' +