openvz: Handle domain obj hash map errors

This makes the driver fail with a clear error message in case of UUID
collisions (for example if somebody copied a container configuration
without updating the UUID) and also raises an error on other hash map
failures.

OpenVZ itself doesn't complain about duplicate UUIDs since this
parameter is only used by libvirt.

src/openvz/openvz_conf.c

@@ -670,8 +670,18 @@ int openvzLoadDomains(struct openvz_driver *driver) {
         openvzReadMemConf(dom->def, veid);
 
         virUUIDFormat(dom->def->uuid, uuidstr);
-        if (virHashAddEntry(driver->domains.objs, uuidstr, dom) < 0)
+        if (virHashLookup(driver->domains.objs, uuidstr)) {
+            openvzError(VIR_ERR_INTERNAL_ERROR,
+                        _("Duplicate container UUID %s detected for %d"),
+                        uuidstr,
+                        veid);
+            goto cleanup;
+        }
+        if (virHashAddEntry(driver->domains.objs, uuidstr, dom) < 0) {
+            openvzError(VIR_ERR_INTERNAL_ERROR,
+                        _("Could not add UUID for container %d"), veid);
             goto cleanup;
+        }
 
         virDomainObjUnlock(dom);
         dom = NULL;