Fix handling of arch:all to arch:any transitions

Given a package where the version in testing is arch:all and uninstallable
on architecture $arch and the version in unstable is arch:any but still
uninstallable on $arch, we need to ensure that installability checks add the
package to $arch's uninstallble list rather than just the list for
${arch}+all.

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

britney.py

@@ -2277,12 +2277,15 @@ class Britney:
                 for p in [x[0] for x in affected if x[1] == arch]:
                     if p not in binaries[arch][0]: continue
                     r = systems[arch].is_installable(p)
-                    if not r and p not in broken:
+                    if not r:
+                        if p not in broken:
                             to_check.append(p)
                             broken.add(p)
                         if not (skip_archall and binaries[arch][0][p][ARCHITECTURE] == 'all'):
+                            if p not in nuninst[arch]:
                                 nuninst[arch].add(p)
-                    elif r and p in broken:
+                    else:
+                        if p in broken:
                             to_check.append(p)
                             broken.remove(p)
                         if not (skip_archall and binaries[arch][0][p][ARCHITECTURE] == 'all'):
@@ -2302,12 +2305,15 @@ class Britney:
                     for p in binaries[arch][0][j][RDEPENDS]:
                         if p in broken or p not in binaries[arch][0]: continue
                         r = systems[arch].is_installable(p)
-                        if not r and p not in broken:
+                        if not r:
+                            if p not in broken:
                                 broken.add(p)
                                 to_check.append(p)
                             if not (skip_archall and binaries[arch][0][p][ARCHITECTURE] == 'all'):
+                                if p not in nuninst[arch]:
                                     nuninst[arch].add(p)
-                        elif r and p in nuninst[arch + "+all"]:
+                        else:
+                            if p in broken:
                                 broken.remove(p)
                                 to_check.append(p)
                             if not (skip_archall and binaries[arch][0][p][ARCHITECTURE] == 'all'):