Pyftpdlib 1.x uses unicode, the provided path will already be unicode and thus…

Pyftpdlib 1.x uses unicode, the provided path will already be unicode and thus does not require decoding.
Detect if the provided path is unicode or not before attempting decoding. Use six.unicode to preserve compatibility with py3.

fs/expose/ftp.py

@@ -28,6 +28,7 @@ from fs.osfs import OSFS
 from fs.errors import convert_fs_errors
 from fs import iotools
 
+from six import unicode
 
 # Get these once so we can reuse them:
 UID = os.getuid()
@@ -105,7 +106,12 @@ class FTPFS(ftpserver.AbstractedFS):
     def chdir(self, path):
         # We dont' use the decorator here, we actually decode a version of the
         # path for use with pyfs, but keep the original for use with pyftpdlib.
-        unipath = unicode(path, self.encoding)
+        if not isinstance(path, unicode):
+            # pyftpdlib 0.7.x
+            unipath = unicode(path, self.encoding)
+        else:
+            # pyftpdlib 1.x
+            unipath = path
         # TODO: can the following conditional checks be farmed out to the fs?
         # If we don't raise an error here for files, then the FTP server will
         # happily allow the client to CWD into a file. We really only want to