OK, perhaps, "substantially modified" might be a better term (I was working from memory):
http://www.bbc.co.uk/news/uk-politics-29066066
Lib Dem Andrew George is urging MPs to back a plan to exempt more people from what critics call the "bedroom tax" and ministers the "spare room subsidy". Lib Dem MPs will get behind Mr George's bill, with Labour also promising to back it. The Tories are understood to have ordered their MPs to vote against the bill on Friday on a three-line whip. Mr George is outlining what he has called "modest reforms" to the system, with more MPs in the Commons chamber than usual for a Friday. If his private member's bill becomes law people who could not be found a smaller home would be exempt from the housing benefit changes."
I believe Mr Andrew's bill was passed with the LibDems voting with Labour.
And once again I'm not arguing the merits of the move. It's just to demonstrate an example of LibDems "making no difference to government policy".