cobra进行代码检查时报错

Question

执行命令：python cobra.py -t test/src时，报错：
Traceback (most recent call last):
File "/root/hgh/sonar/sonar-scanner-3.2.0.1227-linux/bin/cobra/cobra.py", line 18, in
from cobra import main
File "/root/hgh/sonar/sonar-scanner-3.2.0.1227-linux/bin/cobra/cobra/__init__.py", line 22, in
from . import cli, api, config
File "/root/hgh/sonar/sonar-scanner-3.2.0.1227-linux/bin/cobra/cobra/api.py", line 27, in
from flask import Flask, request, render_template, Blueprint
File "/usr/lib/python2.7/site-packages/flask/__init__.py", line 21, in
from .app import Flask, Request, Response
File "/usr/lib/python2.7/site-packages/flask/app.py", line 23, in
from werkzeug.routing import BuildError, Map, RequestRedirect, Rule
File "/usr/lib/python2.7/site-packages/werkzeug/routing.py", line 948
exec(code, globs, locs)
SyntaxError: unqualified exec is not allowed in function '_compile_builder' it contains a nested function with free variables
怎么回事？