--- a/configmix/config.py	Fri Nov 19 12:40:23 2021 +0100
+++ b/configmix/config.py	Fri Nov 19 13:26:53 2021 +0100
@@ -716,7 +716,6 @@
 
     def __init__(self, config, *path):
         super(_JailedConfiguration, self).__init__()
-        self._base = config
         self._path = path
         if path:
             self._pathstr = \
@@ -725,12 +724,26 @@
                 + Configuration._HIER_SEPARATOR
         else:
             self._pathstr = ''
+        self.rebind(config)
+
+    def rebind(self, new_base):
+        """Bind the jail to a new unjailed configuration `new_base`.
+
+        The new configuration base also must have an existing path to
+        the root.
+
+        :param Configuration new_base: the new base
+
+        """
+        if new_base.is_jail:
+            raise TypeError("can only bind to an unjailed configuration")
+        self._base = new_base
         #
         # Early error out if the chroot does not exist but allow
         # degenerated case if `self._path` is empty.
         #
         if self._path:
-            self._base.getvarl(*self._path)
+            new_base.getvarl(*self._path)
 
     def getvarl(self, *path, **kwds):
         return self._base.getvarl(*(self._path + path), **kwds)