here is an attempt at fixing pr1430

canonicalizes to file.m:foo or file.m:-[AClass foo]
which is how it knows that foo is a function and it shouldn't attempt
to look up a method
named foo. not sure if this should be done in decode_line_2 based on
language setting?

so if you move files around or anything you have to reset your
breakpoints, but i would take that over an endless loop.

matt