Merge pull request graphql-python#154 from CaselIT/logging

Replaced sys.excepthook with logging.error

graphql/execution/base.py

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
-import sys
+import logging
+from traceback import format_exception
 
 from ..error import GraphQLError
 from ..language import ast
@@ -11,6 +12,8 @@
 from ..utils.type_from_ast import type_from_ast
 from .values import get_argument_values, get_variable_values
 
+logger = logging.getLogger(__name__)
+
 
 class ExecutionContext(object):
     """Data that must be available at all points during query execution.
@@ -87,8 +90,8 @@ def get_argument_values(self, field_def, field_ast):
         return result
 
     def report_error(self, error, traceback=None):
-        sys.excepthook(type(error), error, getattr(
-            error, 'stack', None) or traceback)
+        exception = format_exception(type(error), error, getattr(error, 'stack', None) or traceback)
+        logger.error(''.join(exception))
         self.errors.append(error)
 
     def get_sub_fields(self, return_type, field_asts):