Hi,

I'm sending a new patch for this Mercury feature request.

The attached patch fixes a previously unnoticed regression that affects 
Objective C parsing (Mercury and Objective C have same file extensions .m).

I had to resort to an added heuristics (implemented in 
`test_objc_is_mercury') to disambiguate Mercury from Objective C source 
files with extension .m.

The patch is cumulative and replaces the former one.

Best,

Fabrice Nicol