[Tests] Fixes in test_tracker_icons.py

* Removed publicbt.org test as server is down
* Replaced ubuntu.ico with ubuntu.png to make the test pass

deluge/tests/test_tracker_icons.py

@@ -1,5 +1,7 @@
 import os
 
+import pytest
+
 import deluge.component as component
 import deluge.ui.tracker_icons
 from deluge.ui.tracker_icons import TrackerIcon, TrackerIcons
@@ -13,6 +15,7 @@ deluge.ui.tracker_icons.PIL_INSTALLED = False
 common.disable_new_release_check()
 
 
+@pytest.mark.internet
 class TrackerIconsTestCase(BaseTestCase):
 
     def set_up(self):
@@ -48,7 +51,7 @@ class TrackerIconsTestCase(BaseTestCase):
 
     def test_get_ubuntu_ico(self):
         # ubuntu.com has inline css which causes HTMLParser issues
-        icon = TrackerIcon(os.path.join(dirname, "ubuntu.ico"))
+        icon = TrackerIcon(os.path.join(dirname, "ubuntu.png"))
         d = self.icons.fetch("www.ubuntu.com")
         d.addCallback(self.assertNotIdentical, None)
         d.addCallback(self.assertEquals, icon)
@@ -62,13 +65,6 @@ class TrackerIconsTestCase(BaseTestCase):
         d.addCallback(self.assertEquals, icon)
         return d
 
-    def test_get_publicbt_ico(self):
-        icon = TrackerIcon(os.path.join(dirname, "publicbt.ico"))
-        d = self.icons.fetch("publicbt.org")
-        d.addCallback(self.assertNotIdentical, None)
-        d.addCallback(self.assertEquals, icon)
-        return d
-
     def test_get_empty_string_tracker(self):
         d = self.icons.fetch("")
         d.addCallback(self.assertIdentical, None)