Fix excuse invalidation checks for arch-specific dependencies

A dependency on an arch-specific package which is not a valid candidate
should lead to the depending package not being a candidate.

For now we ensure that the generated excuses output remains the same,
so that we don't have to wait for consumers to adapt to a new format.
Changing the output format should be revisited at a later point.

See Debian bug #693068.

Signed-off-by: Adam D. Barratt <adam@adam-barratt.org.uk>

britney.py

@@ -1084,6 +1084,9 @@ class Britney(object):
             # for the solving packages, update the excuse to add the dependencies
             for p in packages:
                 if arch not in self.options.break_arches.split():
+                    if p in self.sources['testing'] and self.sources['testing'][p][VERSION] == self.sources[suite][p][VERSION]:
+                        excuse.add_dep("%s/%s" % (p, arch), arch)
+                    else:
                         excuse.add_dep(p, arch)
                 else:
                     excuse.add_break_dep(p, arch)

excuse.py

@@ -135,11 +135,15 @@ class Excuse(object):
                 (self.daysold, self.mindays))
         for x in self.htmlline:
             res = res + "<li>" + x + "\n"
-        for x in sorted(self.deps):
+        lastdep = ""
+        for x in sorted(self.deps, lambda x,y: cmp(x.split('/')[0], y.split('/')[0])):
+            dep = x.split('/')[0]
+            if dep == lastdep: continue
+            lastdep = dep
             if x in self.invalid_deps:
-                res = res + "<li>Depends: %s <a href=\"#%s\">%s</a> (not considered)\n" % (self.name, x, x)
+                res = res + "<li>Depends: %s <a href=\"#%s\">%s</a> (not considered)\n" % (self.name, dep, dep)
             else:
-                res = res + "<li>Depends: %s <a href=\"#%s\">%s</a>\n" % (self.name, x, x)
+                res = res + "<li>Depends: %s <a href=\"#%s\">%s</a>\n" % (self.name, dep, dep)
         for (n,a) in self.break_deps:
             if n not in self.deps:
                 res += "<li>Ignoring %s depends: <a href=\"#%s\">%s</a>\n" % (a, n, n)