Fix migration for sources with old cruft that isn't in testing

A package can have old cruft no longer in testing, which can't
migrate because it depends on old libraries or packages that
aren't in testing anymore, preventing migration.

There's no point in trying to migrate old cruft that has already
been removed in testing anyway, so don't do that.

Signed-off-by: Emilio Pozuelo Monfort <pochu@debian.org>
Signed-off-by: Niels Thykier <niels@thykier.net>

britney.py

@@ -2024,6 +2024,12 @@ class Britney(object):
                                 rms.remove((rm_b, rm_v, rm_p))
                     continue
 
+                # Don't add the binary if it is old cruft that is no longer in testing
+                if (parch not in self.options.fucked_arches and
+                    source_data[VERSION] != self.binaries[suite][parch][0][binary][SOURCEVER] and
+                    binary not in binaries_t[parch][0]):
+                    continue
+
                 adds.add(pkg_id)
 
         return (adds, rms, smoothbins)