=== modified file 'bzrlib/index.py'
--- bzrlib/index.py	2011-12-19 13:23:58 +0000
+++ bzrlib/index.py	2012-10-02 23:04:47 +0000
@@ -1500,6 +1500,7 @@
         parent_map = {}
         keys_to_lookup = set(keys)
         generation = 0
+        from bzrlib.btree_index import BTreeBuilder
         while keys_to_lookup:
             # keys that *all* indexes claim are missing, stop searching them
             generation += 1
@@ -1509,6 +1510,15 @@
             #                                   len(parent_map),
             #                                   len(missing_keys))
             for index_idx, index in enumerate(self._indices):
+                # Skip BTreeBuilder instances as ... they don't really
+                # implement _find_ancestors(). This is not a real fix as I
+                # don't understand bzr data model but at least it makes bzr
+                # fast-import work for me.
+                if isinstance(index, BTreeBuilder):
+                    trace.mutter("Skipping incompatible index %s", index)
+                    continue
+                else:
+                    trace.mutter("Looking in %s", index)
                 # TODO: we should probably be doing something with
                 #       'missing_keys' since we've already determined that
                 #       those revisions have not been found anywhere