diff --git a/alembic/runtime/migration.py b/alembic/runtime/migration.py
index e811a36..6711841 100644
--- a/alembic/runtime/migration.py
+++ b/alembic/runtime/migration.py
@@ -495,6 +495,8 @@ class HeadMaintainer(object):
                 self._insert_version(insrev)
             self._update_version(update_from_rev, update_to_rev)
         else:
+            import pdb
+            pdb.set_trace()
             from_, to_ = step.update_version_num(self.heads)
             log.debug("update %s to %s", from_, to_)
             self._update_version(from_, to_)
@@ -572,7 +574,10 @@ class RevisionStep(MigrationStep):
 
     @property
     def _has_scalar_down_revision(self):
-        return len(self.revision._all_down_revisions) == 1
+        if self.is_upgrade:
+            return len(self.revision._all_down_revisions) == 1
+        else:
+            return len(self.revision._versioned_down_revisions) == 1
 
     def should_delete_branch(self, heads):
         if not self.is_downgrade:
@@ -588,6 +593,7 @@ class RevisionStep(MigrationStep):
         elif len(downrevs) == 1:
             downrev = self.revision_map.get_revision(downrevs[0])
 
+#            if not downrev.is_branch_point:
             if not downrev._is_real_branch_point:
                 return False
 
@@ -699,7 +705,7 @@ class RevisionStep(MigrationStep):
         if not self.is_downgrade:
             return False
 
-        downrevs = self.revision._all_down_revisions
+        downrevs = self.revision._versioned_down_revisions
 
         if self.revision.revision in heads and len(downrevs) > 1:
             return True
@@ -707,6 +713,7 @@ class RevisionStep(MigrationStep):
         return False
 
     def update_version_num(self, heads):
+
         if not self._has_scalar_down_revision:
             downrev = heads.intersection(self.revision._all_down_revisions)
             assert len(downrev) == 1, \