Reloacating debugger_history_file doesn't work

I am trying to modify the path ~/.pdbhistory to another path by
```
c = get_config()
c.TerminalInteractiveShell.debugger_history_file='/newplace/.pdbhistory'
```
in IPYTHONDIR/ipython_config.py

but it doesn't work! 
Any suggestions on how to modify the path would be appreciated!