python cgi 程序中加入import访问显示空白，不加入import cgi 访问正常？

Question

## 加入import cgi

#!/usr/bin/python
#coding: UTF-8

import cgitb
cgitb.enable()
import cgi
import sqlite3

# 创建 FieldStorage 的实例化
#form = cgi.FieldStorage() 

# 获取数据
#username = form.getvalue('username')
#password  = form.getvalue('password')

#data = [ { 'username' : username, 'password' : password} ]

print "Content-type: text/html"
print

print "{\"code\":0,\"msg\":\"登陆成功\",\"data\":2222}"

web访问：

不加import cgi

#!/usr/bin/python
#coding: UTF-8

#import cgitb
#cgitb.enable()
#import cgi
import sqlite3

# 创建 FieldStorage 的实例化
#form = cgi.FieldStorage() 

# 获取数据
#username = form.getvalue('username')
#password  = form.getvalue('password')

#data = [ { 'username' : username, 'password' : password} ]

print "Content-type: text/html"
print

print "{\"code\":0,\"msg\":\"登陆成功\",\"data\":2222}"

访问正常：