storage: fix hot reload with named identification

Currently hot reload failes, when named identification is used.
It is cause by the fact, that we still pass uuid in storage.cfg
during reload.

Let's pass id instead of UUID. It's either uuid or name, depeding on
identification_mode. If reload is done from the old version, where no
replica.id exists, we fall back to replica.uuid.

Closes #464

NO_DOC=bugfix

test/storage-luatest/storage_1_test.lua

@@ -183,3 +183,28 @@ test_group.test_local_call = function(g)
         box.func.sum:drop()
     end)
 end
+
+--
+-- gh-464: hot reload with named identification is broken.
+--
+test_group.test_named_hot_reload = function(g)
+    t.run_only_if(vutil.feature.persistent_names)
+    local new_cfg_template = table.deepcopy(cfg_template)
+    new_cfg_template.identification_mode = 'name_as_key'
+    new_cfg_template.sharding['replicaset'] = new_cfg_template.sharding[1]
+    new_cfg_template.sharding[1] = nil
+
+    g.replica_1_a:exec(function()
+        box.cfg{instance_name = 'replica_1_a', replicaset_name = 'replicaset'}
+    end)
+    local new_global_cfg = vtest.config_new(new_cfg_template)
+    vtest.cluster_cfg(g, new_global_cfg)
+
+    -- gh-464: hot reload with named identification is broken.
+    g.replica_1_a:exec(function()
+        package.loaded['vshard.storage'] = nil
+        local ok, storage = pcall(require, 'vshard.storage')
+        ilt.assert_equals(ok, true)
+        _G.vshard.storage = storage
+    end)
+end

vshard/storage/init.lua

@@ -4036,7 +4036,8 @@ if not rawget(_G, MODULE_INTERNALS) then
 else
     reload_evolution.upgrade(M)
     if M.current_cfg then
-        storage_cfg(M.current_cfg, M.this_replica.uuid, true)
+        storage_cfg(M.current_cfg, M.this_replica.id or M.this_replica.uuid,
+                    true)
     end
     M.module_version = M.module_version + 1
     -- Background fibers could sleep waiting for bucket changes.