Fixed tag merge bug.

app/models/tag.rb

@@ -216,7 +216,7 @@ rename tag items
       already_existing_tag = Tag::Item.lookup(name: new_tag_name)
 
       # check if no remame is needed
-      return true if new_tag_name.downcase == old_tag_item.name.downcase
+      return true if new_tag_name == old_tag_item.name
 
       # merge old with new tag if already existing
       if already_existing_tag

test/unit/tag_test.rb

@@ -342,4 +342,53 @@ class TagTest < ActiveSupport::TestCase
     assert(tags_ticket2.include?('some rename tag2'))
 
   end
+
+  test 'tags - rename and merge tag with existing tag' do
+
+    ticket1 = Ticket.create(
+      title: 'rename tag1',
+      group: Group.lookup(name: 'Users'),
+      customer_id: 2,
+      updated_by_id: 1,
+      created_by_id: 1,
+    )
+    ticket2 = Ticket.create(
+      title: 'rename tag2',
+      group: Group.lookup(name: 'Users'),
+      customer_id: 2,
+      updated_by_id: 1,
+      created_by_id: 1,
+    )
+
+    ticket1.tag_add('tagname1', 1)
+    ticket1.tag_add('tagname2', 1)
+
+    ticket2.tag_add('Tagname2', 1)
+
+    tags_ticket1 = ticket1.tag_list
+    assert_equal(2, tags_ticket1.count)
+    assert(tags_ticket1.include?('tagname1'))
+    assert(tags_ticket1.include?('tagname2'))
+
+    tags_ticket2 = ticket2.tag_list
+    assert_equal(1, tags_ticket2.count)
+    assert(tags_ticket2.include?('Tagname2'))
+
+    tag_item1 = Tag::Item.lookup(name: 'Tagname2')
+    Tag::Item.rename(
+      id:            tag_item1.id,
+      name:          'tagname2',
+      created_by_id: 1,
+    )
+
+    tags_ticket1 = ticket1.tag_list
+    assert_equal(2, tags_ticket1.count)
+    assert(tags_ticket1.include?('tagname1'))
+    assert(tags_ticket1.include?('tagname2'))
+
+    tags_ticket2 = ticket2.tag_list
+    assert_equal(1, tags_ticket2.count)
+    assert(tags_ticket2.include?('tagname2'))
+
+  end
 end