[boost] Filesystem breaking change?

Beman, The recent update to Boost.Filesystem has broken bcp in a way I'm not sure how to fix. The problem is that while scanning for header dependencies it comes across some platform dependent names ( :sys:stat.h ) and then checks for the existence of that name in various places such as <tools/build/jam_src/:sys:stat.h>. Obviously such checks should fail, but rather than just saying "no the file doesn't exist" the function exists is throwing an exception. IMO there's no real need for an exception in this case is there? Many thanks, John.