Rewriter does not include source file in locations

[jonathan-dilorenzo]

It seems the rewriter does not include the source file in location information for some reason.

When I use ocamlc to spit out new source and print a location (in my AST mapper) I get:

File "examples/test.ml", line 3, characters 0-166

When I use the rewriter I get:

File "", line 3, characters 0-166