=== modified file './aptsources/sourceslist.py'
--- ./aptsources/sourceslist.py	2012-06-12 07:30:56 +0000
+++ ./aptsources/sourceslist.py	2012-08-29 14:41:23 +0000
@@ -313,7 +313,7 @@
         for source in sources:
             # if there is a repo with the same (type, uri, dist) just add the
             # components
-            if source.disabled and set(source.comps) == comps:
+            if source.disabled and set(source.comps) == set(comps):
                 source.disabled = False
                 return source
             elif not source.disabled:

=== modified file './tests/test_aptsources.py'
--- ./tests/test_aptsources.py	2011-10-19 15:40:03 +0000
+++ ./tests/test_aptsources.py	2012-08-29 14:41:47 +0000
@@ -233,6 +233,20 @@
         for key in found:
             self.assertEqual(found[key], 1)
 
+    def test_enable_disabled(self):
+        """LP: #1042916: Test enabling a disabled entry"""
+        apt_pkg.config.set("Dir::Etc::sourcelist", "data/aptsources/"
+                           "sources.list")
+        sources = aptsources.sourceslist.SourcesList(True, self.templates)
+        disabled = sources.add("deb", "http://fi.archive.ubuntu.com/ubuntu/",
+                    "precise",
+                    ["main"])
+        disabled.disabled = True
+        enabled = sources.add("deb", "http://fi.archive.ubuntu.com/ubuntu/",
+                    "precise",
+                    ["main"])
+        self.assertEqual(disabled, enabled)
+        self.assertFalse(disabled.disabled)
 
 if __name__ == "__main__":
     os.chdir(os.path.dirname(__file__))