authn: Allow users to store plugin ID's starting with the legacy plugin prefix.

rhodecode/model/validators.py

@@ -38,9 +38,9 b' from sqlalchemy.sql.expression import tr'
 from sqlalchemy.util import OrderedSet
 from webhelpers.pylonslib.secure_form import authentication_token
 
+from rhodecode.authentication import legacy_plugin_prefix
 from rhodecode.config.routing import ADMIN_PREFIX
 from rhodecode.lib.auth import HasRepoGroupPermissionAny, HasPermissionAny
-from rhodecode.lib.exceptions import LdapImportError
 from rhodecode.lib.utils import repo_name_slug, make_db_config
 from rhodecode.lib.utils2 import safe_int, str2bool, aslist, md5
 from rhodecode.lib.vcs.backends.git.repository import GitRepository
@@ -995,12 +995,11 b' def ValidAuthPlugins():'
             from rhodecode.authentication.base import loadplugin
             module_list = value
             unique_names = {}
+            try:
             for module in module_list:
+                    if module.startswith(legacy_plugin_prefix):
+                        continue
                 plugin = loadplugin(module)
-                if plugin is None:
-                    raise formencode.Invalid(
-                        _("Can't find plugin with id '{}'".format(module)),
-                        value, state)
                 plugin_name = plugin.name
                 if plugin_name in unique_names:
                     msg = M(self, 'import_duplicate', state,
@@ -1008,6 +1007,8 b' def ValidAuthPlugins():'
                             next_to_load=plugin_name)
                     raise formencode.Invalid(msg, value, state)
                 unique_names[plugin_name] = plugin
+            except (KeyError, AttributeError, TypeError) as e:
+                raise formencode.Invalid(str(e), value, state)
 
     return _validator