python调用git出错

#报错信息
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Python27\lib\site-packages\git\__init__.py", line 85, in <module>
    raise ImportError('Failed to initialize: {0}'.format(exc))
ImportError: Failed to initialize: Bad git executable.
The git executable must be specified in one of the following ways:
    - be included in your $PATH
    - be set via $GIT_PYTHON_GIT_EXECUTABLE
    - explicitly set via git.refresh()

All git commands will error until this is rectified.

This initial warning can be silenced or aggravated in the future by setting the
$GIT_PYTHON_REFRESH environment variable. Use one of the following values:
    - quiet|q|silence|s|none|n|0: for no warning or exception
    - warn|w|warning|1: for a printed warning
    - error|e|raise|r|2: for a raised exception

Example:
    export GIT_PYTHON_REFRESH=quiet

#出错原因：git环境变量设置问题
#简便解决办法：在导入包的上方增加以下代码
import os
os.environ["GIT_PYTHON_REFRESH"] = "quiet"