britney: Check for mismatched packages between suites.

britney assumes that a package build is uniquely described by its
name, version and architecture. Particularly when constructing
Packages files by hand for testing purposes this assumption can be
violated, leading to confusing behaviour. This change makes britney
look for such mismatches, and report if any are found.

britney.py

@@ -288,6 +288,9 @@ class Britney(object):
                 # properly initialised, so insert two empty dicts
                 # here.
                 self.binaries['pu'][arch] = ({}, {})
+
+            self._check_mismatches(arch)
+
         self._build_installability_tester(self.options.architectures)
 
         if not self.options.nuninst_cache:
@@ -328,6 +331,40 @@ class Britney(object):
         self.excuses = []
         self.dependencies = {}
 
+    def _check_mismatches(self, arch):
+        suites = [s for s in self.binaries if arch in self.binaries[s]]
+
+        check_field_name = dict( (globals()[fn], fn) for fn in
+               ("SOURCE SOURCEVER ARCHITECTURE MULTIARCH"
+                 + " DEPENDS CONFLICTS PROVIDES ESSENTIAL").split() )
+        check_fields = check_field_name.keys()
+
+        any_mismatch = False
+        for s1, s2 in product(suites, suites):
+            if s1 >= s2: continue
+            s1_pkgs = self.binaries[s1][arch][0]
+            s2_pkgs = self.binaries[s2][arch][0]
+            pkgs = set(s1_pkgs) & set(s2_pkgs)
+            for p in pkgs:
+                if s1_pkgs[p][VERSION] != s2_pkgs[p][VERSION]: continue
+                bad = []
+                for f in check_fields:
+                    if s1_pkgs[p][f] != s2_pkgs[p][f]:
+                        bad.append((f, s1_pkgs[p][f], s2_pkgs[p][f]))
+
+                if bad:
+                    any_mismatch = True
+                    self.__log("Mismatch found %s %s %s differs in %s vs %s" % (
+                        p, s1_pkgs[p][VERSION], arch, s1, s2), type="E")
+                    for f, v1, v2 in bad:
+                        self.__log(" ... %s %s != %s" % (check_field_name[f], v1, v2))
+
+        # test suite doesn't appreciate aborts of this nature
+        #if any_mismatch:
+        #    self.__log("Mismatches found, exiting.", type="I")
+        #    sys.exit(1)
+        return
+
     def __parse_arguments(self):
         """Parse the command line arguments