Decode script arguments using file system encoding

This mimics Python 3's behavior, where sys.argv is automatically decoded
using file system encoding, as returned by sys.getfilesystemencoding(). This
includes reimplementation of os.fsdecode() from Python 3.

Reviewed-By: Petr Viktorin <pviktori@redhat.com>

ipapython/ipautil.py

@@ -1352,3 +1352,22 @@ def private_ccache(path=None):
 
         if os.path.exists(path):
             os.remove(path)
+
+
+if six.PY2:
+    def fsdecode(value):
+        """
+        Decode argument using the file system encoding, as returned by
+        `sys.getfilesystemencoding()`.
+        """
+        if isinstance(value, six.binary_type):
+            return value.decode(sys.getfilesystemencoding())
+        elif isinstance(value, six.text_type):
+            return value
+        else:
+            raise TypeError("expect {0} or {1}, not {2}".format(
+                six.binary_type.__name__,
+                six.text_type.__name__,
+                type(value).__name__))
+else:
+    fsdecode = os.fsdecode  #pylint: disable=no-member