os.walk 排除 .svn 文件夹

我有一个脚本，我想用它来更改整个项目文件夹结构中的重复字符串。一旦更改，我就可以将其签入 SVN。但是，当我运行脚本时，它会进入我希望它忽略的 .svn 文件夹。我怎样才能实现这个目标？代码如下，谢谢。

import os
import sys

replacement = "newString"
toReplace = "oldString"
rootdir = "pathToProject"


for root, subFolders, files in os.walk(rootdir):
  print subFolders
  if not ".svn" in subFolders:
    for file in files:
      fileParts = file.split('.')
      if len(fileParts) > 1:
        if not fileParts[len(fileParts)-1] in ["dll", "suo"]:
          fpath = os.path.join(root, file)
          with open(fpath) as f:
            s = f.read()
          s = s.replace(toReplace, replacement)
          with open(fpath, "w") as f:
            f.write(s)

print "DONE"

尝试这个：

for root, subFolders, files in os.walk(rootdir):
    if '.svn' in subFolders:
      subFolders.remove('.svn')

然后继续处理。