Re: [BUG] commit walk machinery is dangerous !

> Nicolas Pitre <nico@cam.org> writes:
> 
> > It is those with semantic meaning (e.g. object doesn't exist) which 
> > should be audited, especially if used in the context of repository 
> > modification, which pretty much limits it to the test case I produced.
> 
> I've been wondering if we should make the change 8eca0b4 (implement some
> resilience against pack corruptions, 2008-06-23) less aggressive.
> 
> It makes loose objects and data from other packs to be used as fallback
> where we used to just punt, which is a genuine improvement for "salvaging"
> mode of operation, but at the same time, it now forbids the callers to
> expect that the objects they learned to exist from has_sha1_file() or
> nth_packed_object_sha1() should never result NULL return value from
> read_sha1_file().
> 
> It may make it safe again to fail if you cannot salvage using fallback
> method after all.  Something like the attached.