fix copying when file is already where it needs to be

NEWS

@@ -10,6 +10,8 @@
 * Fixed a spurious crash when LANG or a related environment variable is
   set to an invalid value (such as 'UTF-8' on some installations of Mac
   OS X).
+* Fixed an error when trying to copy a file that is already at its
+  destination.
 
 1.0b5
 -----

beets/library.py

@@ -328,10 +328,11 @@ class Item(object):
         # Create necessary ancestry for the move.
         _mkdirall(dest)
         
-        if copy:
-            shutil.copy(self.path, dest)
-        else:
-            shutil.move(self.path, dest)
+        if not shutil._samefile(self.path, dest):
+            if copy:
+                shutil.copy(self.path, dest)
+            else:
+                shutil.move(self.path, dest)
             
         # Either copying or moving succeeded, so update the stored path.
         self.path = dest

test/test_files.py

@@ -72,6 +72,18 @@ class MoveTest(unittest.TestCase):
     def test_move_changes_path(self):
         self.i.move(self.lib)
         self.assertEqual(self.i.path, beets.library._normpath(self.dest))
+
+    def test_copy_already_at_destination(self):
+        self.i.move(self.lib)
+        old_path = self.i.path
+        self.i.move(self.lib, copy=True)
+        self.assertEqual(self.i.path, old_path)
+
+    def test_move_already_at_destination(self):
+        self.i.move(self.lib)
+        old_path = self.i.path
+        self.i.move(self.lib, copy=False)
+        self.assertEqual(self.i.path, old_path)
     
 class HelperTest(unittest.TestCase):
     def test_ancestry_works_on_file(self):