Properly iterate through values

the value of Manifest.projects has changed from being the dictionary
to the values of the dictionary.  Here we handle this change
correctly on a PostRepoUpgrade.

From a `git diff v1.12.7 -- manifest_xml.py`:
+  @property
   def projects(self):
     self._Load()
-    return self._projects
+    return self._paths.values()

self._paths does contain the projects according to this line of
manifest_xml.py:
484      self._paths[project.relpath] = project

Change-Id: I141f8d5468ee10dfb08f99ba434004a307fed810

subcmds/sync.py

@@ -702,7 +702,7 @@ def _PostRepoUpgrade(manifest, quiet=False):
   wrapper = WrapperModule()
   if wrapper.NeedSetupGnuPG():
     wrapper.SetupGnuPG(quiet)
-  for project in manifest.projects.values():
+  for project in manifest.projects:
     if project.Exists:
       project.PostRepoUpgrade()