diff -r 265e36e277f3 Doc/library/shutil.rst
--- a/Doc/library/shutil.rst	Mon Jul 16 17:11:10 2012 +0200
+++ b/Doc/library/shutil.rst	Tue Jul 17 07:57:42 2012 +0900
@@ -52,7 +52,7 @@
    Copy the contents (no metadata) of the file named *src* to a file named
    *dst* and return *dst*.  *dst* must be the complete target file name; look at
    :func:`shutil.copy` for a copy that accepts a target directory path.  If
-   *src* and *dst* are the same files, :exc:`Error` is raised.
+   *src* and *dst* are the same files, :exc:`SameFileError` is raised.
 
    The destination location must be writable; otherwise,  an :exc:`OSError` exception
    will be raised. If *dst* already exists, it will be replaced.   Special files
@@ -63,6 +63,10 @@
    a new symbolic link will be created instead of copying the
    file *src* points to.
 
+
+   .. versionchanged:: 3.????
+      Added raising :exc:`SameFileError`.
+
    .. versionchanged:: 3.3
       :exc:`IOError` used to be raised instead of :exc:`OSError`.
       Added *follow_symlinks* argument.
@@ -261,6 +265,12 @@
 
    .. versionadded:: 3.3
 
+.. exception:: SameFileError
+
+   This exception is raised if source and destination in :func:`move`
+   are the same files. It is a subclass of :exc:`Error`.
+
+   .. versionadded:: 3.????
 
 .. function:: which(cmd, mode=os.F_OK | os.X_OK, path=None)
 
diff -r 265e36e277f3 Lib/shutil.py
--- a/Lib/shutil.py	Mon Jul 16 17:11:10 2012 +0200
+++ b/Lib/shutil.py	Tue Jul 17 07:57:42 2012 +0900
@@ -42,6 +42,10 @@
 class Error(EnvironmentError):
     pass
 
+class SameFileError(Error):
+    """Raised when source and destination are the same files."""
+    pass
+
 class SpecialFileError(EnvironmentError):
     """Raised when trying to do a kind of operation (e.g. copying) which is
     not supported on a special file (e.g. a named pipe)"""
@@ -90,7 +94,7 @@
 
     """
     if _samefile(src, dst):
-        raise Error("`%s` and `%s` are the same file" % (src, dst))
+        raise SameFileError("{!r} and {!r} are the same file".format(src, dst))
 
     for fn in [src, dst]:
         try:
@@ -215,6 +219,9 @@
     If follow_symlinks is false, symlinks won't be followed. This
     resembles GNU's "cp -P src dst".
 
+    If the source and destination files are same, a SameFileError exception
+    will be raised.
+
     """
     if os.path.isdir(dst):
         dst = os.path.join(dst, os.path.basename(src))
diff -r 265e36e277f3 Lib/test/test_shutil.py
--- a/Lib/test/test_shutil.py	Mon Jul 16 17:11:10 2012 +0200
+++ b/Lib/test/test_shutil.py	Tue Jul 17 07:57:42 2012 +0900
@@ -18,7 +18,8 @@
                     register_archive_format, unregister_archive_format,
                     get_archive_formats, Error, unpack_archive,
                     register_unpack_format, RegistryError,
-                    unregister_unpack_format, get_unpack_formats)
+                    unregister_unpack_format, get_unpack_formats,
+                    SameFileError)
 import tarfile
 import warnings
 
@@ -1215,6 +1216,16 @@
         self.assertTrue(os.path.exists(rv))
         self.assertEqual(read_file(src_file), read_file(dst_file))
 
+    def test_copyfile_same_file(self):
+        # copyfile() should raise SameFileError if The source and destination 
+        # are the same.
+        src_dir = self.mkdtemp()
+        src_file = os.path.join(src_dir, 'foo')
+        write_file(src_file, 'foo')
+
+        with self.assertRaises(SameFileError):
+            rv = shutil.copyfile(src_file, src_file)
+
     def test_copytree_return_value(self):
         # copytree returns its destination path.
         src_dir = self.mkdtemp()