Automatically detecting package file conflicts without dependency conflicts?

[Josh Triplett <josh@joshtriplett.org>]

Bugs like 806253 come up fairly regularly in unstable: two packages
contain the same file, but don't have a Conflicts or Replaces
relationship.  Renamed packages seem like the most common case, though
this can happen other ways as well.

The archive software already does a variety of checks on packages before
accepting them into the archive.  Do we have enough data and metadata
available that the archive software could automatically reject uploads
of .deb files that contain the same file path as another package without
a Conflicts or Replaces expressed against that package?

- Josh Triplett