fix PluginBase import bug

shards/mishards/router/factory.py

 import os
 import logging
 from functools import partial
-# from pluginbase import PluginBase
-# import importlib
-from utils.pluginextension import MiPluginBase
+from utils.pluginextension import MiPluginBase as PluginBase
 
 logger = logging.getLogger(__name__)
 
@@ -11,8 +9,8 @@ here = os.path.abspath(os.path.dirname(__file__))
 get_path = partial(os.path.join, here)
 
 PLUGIN_PACKAGE_NAME = 'router.plugins'
-plugin_base = MiPluginBase(package=PLUGIN_PACKAGE_NAME,
-                           searchpath=[get_path('./plugins')])
+plugin_base = PluginBase(package=PLUGIN_PACKAGE_NAME,
+                         searchpath=[get_path('./plugins')])
 
 
 class RouterFactory(object):

shards/tracer/factory.py

 import os
 import logging
 from functools import partial
-from pluginbase import PluginBase
+from utils.pluginextension import MiPluginBase as PluginBase
+# from pluginbase import PluginBase
 from tracer import Tracer
 
 

shards/utils/pluginextension.py

-import importlib
+import importlib.util
 from pluginbase import PluginBase, PluginSource
 
 
 class MiPluginSource(PluginSource):
     def load_plugin(self, name):
-        if '.' in name:
-            raise ImportError('Plugin names cannot contain dots.')
-        with self:
-            return importlib.import_module(self.base.package + '.' + name)
+        plugin = super().load_plugin(name)
+        spec = importlib.util.spec_from_file_location(self.base.package + '.' + name, plugin.__file__)
+        plugin = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(plugin)
+        return plugin
 
 
 class MiPluginBase(PluginBase):