ghc 6.10.4 infix declarations and '\' bug or not ?

[John Lask]

in declaring fixity for an operator (\\) to get it to compile using ghc 
6.10.4, I needed to use the following code

infixl 9 \\\
(\\) a b = etc ...

where I assume the first \ escapes the second \, using infixl 9 \\ generates 
a syntax error

infixl 9 \\  used to compile no problems with ghc 6.8.2

what is going on here ? why do I now need to add an additional \ ?, where is 
this change documented ?, is this a bug?