While using shutil.copytree() and the source containing symbolic directory (not symbolic file), an error will be raised. I checked the source code and found an obvlous mistake: shutil.copytree() using os.path.islink() to checker whether the source is a symbolic link, it's okay, but after doing this, os.path.isdir() should be called because a symbolic link may either be a file or a directry, shutil.copytree() just treated all of them as file, and invoke copy_function to copy it, so error happens.

I don't know whether newer versions have fixed this bug, but I googled it and found nothing.

Thanks for the report. The bug is still present in the 3.4 and default (what will become the 3.5 release) branches; the 3.3 branch now only accepts security fixes.  2.7 does not fail.  Would you be interested in producing a patch for the problem?

Here's a patch. I'm getting the following error without modify Lib/shutil.py:

======================================================================
ERROR: test_copytree_symbolic_directory (test.test_shutil.TestShutil)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/berker/projects/cpython-default/Lib/test/test_shutil.py", line 650, in test_copytree_symbolic_directory
    shutil.copytree(src_dir, dst_dir)
  File "/home/berker/projects/cpython-default/Lib/shutil.py", line 342, in copytree
    raise Error(errors)
shutil.Error: [('/tmp/tmpiy30_34s/src/link', '/tmp/tmpiy30_34s/dst/link', "[Errno 21] Is a directory: '/tmp/tmpiy30_34s/src/link'")]

Berker Peksag, I don't think your patch is okay.
When symlinks is set to true, it should copy the symbolic link of the directory. Your code is calling copytree instead.
I think the following patch is working, no errors on regression tests.

I have tested both patches on CentOS 6.4 and Eduardo Seabra:s patch works correctly with symlinks=True

I ran across this bug too. Applying Eduardo's patch got my package
working under Py 3.4

Here's my patch (I submitted the duplicate issue). I think it's functionally the same as Eduardo's, but it also adds a test.

New changeset e807f1d81cb6 by Berker Peksag in branch '3.4':
Issue #21697: shutil.copytree() now correctly handles symbolic links that point to directories.
https://hg.python.org/cpython/rev/e807f1d81cb6

New changeset 31f4041b9286 by Berker Peksag in branch '3.5':
Issue #21697: shutil.copytree() now correctly handles symbolic links that point to directories.
https://hg.python.org/cpython/rev/31f4041b9286

New changeset 8f65be73eb3a by Berker Peksag in branch 'default':
Issue #21697: shutil.copytree() now correctly handles symbolic links that point to directories.
https://hg.python.org/cpython/rev/8f65be73eb3a

Thanks for the patches and testing!