Don't leave dangling map if adding an indirect map fails

When using the add_indirect helper we create a new map and then add a key
for it all in one step. If adding the key fails for any reason be sure to
remove the map we added.

https://fedorahosted.org/freeipa/ticket/1520

tests/test_xmlrpc/test_automount_plugin.py

@@ -266,6 +266,17 @@ class test_automount_indirect(XMLRPC_test):
         assert res
         assert_attr_equal(res, 'automountmapname', self.mapname)
 
+    def test_1a_automountmap_add_indirect(self):
+        """
+        Test adding a duplicate indirect map.
+        """
+        try:
+            api.Command['automountmap_add_indirect'](self.locname, self.mapname, **self.map_kw)['result']
+        except errors.DuplicateEntry:
+            pass
+        else:
+            assert False
+
     def test_2_automountmap_show(self):
         """
         Test the `xmlrpc.automountmap_show` method.