Fix ipa migrate-ds when it finds a search reference

When ipa migrate-ds finds user entries and a search reference, it complains
that the LDAP search did not return any result and does not migrate the
entries or the groups.

The issue comes from LDAPClient._convert_result which returns an empty result
list when the input is a search reference. In turn LDAPClient.find_entries
assumes that the empty result list corresponds to a Search Result Done and
returns without any entry.

The fix examines first the objtype returned by self.conn.result3. If it is
a search result done, then the loop can be exited. Otherwise (referral or
entry), _convert_result is called and the result (if not empty) is appended
to the list of returned entries.

https://fedorahosted.org/freeipa/ticket/6358

Reviewed-By: Martin Basti <mbasti@redhat.com>

ipaserver/plugins/migration.py

@@ -746,8 +746,7 @@ migration process might be incomplete\n''')
                 entries, truncated = ds_ldap.find_entries(
                     search_filter, ['*'], search_bases[ldap_obj_name],
                     scope,
-                    time_limit=0, size_limit=-1,
-                    search_refs=True    # migrated DS may contain search references
+                    time_limit=0, size_limit=-1
                 )
             except errors.NotFound:
                 if not options.get('continue',False):