old_contents: """
  sentry.utils.imports
  ~~~~~~~~~~~~~~~~~~~~
  
  :copyright: (c) 2010-2014 by the Sentry Team, see AUTHORS for more details.
  :license: BSD, see LICENSE for more details.
  """
  from __future__ import absolute_import
  
  import pkgutil
  import six
  
  
  class ModuleProxyCache(dict):
      def __missing__(self, key):
          if '.' not in key:
              return __import__(key)
  
          module_name, class_name = key.rsplit('.', 1)
  
          module = __import__(module_name, {}, {}, [class_name])
          handler = getattr(module, class_name)
  
          # We cache a NoneType for missing imports to avoid repeated lookups
          self[key] = handler
  
          return handler
  
  _cache = ModuleProxyCache()
  
  
  def import_string(path):
      """
      Path must be module.path.ClassName
  
      >>> cls = import_string('sentry.models.Group')
      """
      result = _cache[path]
      return result
  
  
  def import_submodules(context, root_module, path):
      """
      Import all submodules and register them in the ``context`` namespace.
  
      >>> import_submodules(locals(), __name__, __path__)
      """
      for loader, module_name, is_pkg in pkgutil.walk_packages(path, root_module + '.'):
          module = loader.find_module(module_name).load_module(module_name)
          for k, v in six.iteritems(vars(module)):
              if not k.startswith('_'):
                  context[k] = v
          context[module_name] = module
  
new_contents: """
  sentry.utils.imports
  ~~~~~~~~~~~~~~~~~~~~
  
  :copyright: (c) 2010-2014 by the Sentry Team, see AUTHORS for more details.
  :license: BSD, see LICENSE for more details.
  """
  from __future__ import absolute_import
  
  import pkgutil
  import six
  
  
  class ModuleProxyCache(dict):
      def __missing__(self, key):
          if '.' not in key:
              return __import__(key)
  
          module_name, class_name = key.rsplit('.', 1)
  
          module = __import__(module_name, {}, {}, [class_name])
          handler = getattr(module, class_name)
  
          # We cache a NoneType for missing imports to avoid repeated lookups
          self[key] = handler
  
          return handler
  
  _cache = ModuleProxyCache()
  
  
  def import_string(path):
      """
      Path must be module.path.ClassName
  
      >>> cls = import_string('sentry.models.Group')
      """
      result = _cache[path]
      return result
  
  
  def import_submodules(context, root_module, path):
      """
      Import all submodules and register them in the ``context`` namespace.
  
      >>> import_submodules(locals(), __name__, __path__)
      """
      for loader, module_name, is_pkg in pkgutil.walk_packages(path, root_module + '.'):
          # this causes a Runtime error with model conflicts
          # module = loader.find_module(module_name).load_module(module_name)
          module = __import__(module_name, globals(), locals(), ['__name__'])
          for k, v in six.iteritems(vars(module)):
              if not k.startswith('_'):
                  context[k] = v
          context[module_name] = module
  
subject: Correct import behavior to prevent Runtime error