本错误是因为操作终端的时候 vi Podfile 写成 vi podfile
官方的说法：
Case-changed files
SVN repositories and working copies are generally case-sensitive. This can cause problems when working on a case-insensitive operating system, like Microsoft Windows or some file systems on Apple Mac OS, and changing the file name's case (upper-case to lower-case, etc.). Because of SVN's working copy format and the pristine copies, it's technically not possible to handle such a file name case change.
One solution is to avoid this situation by either only performing file name case changes on an operating system which supports case-sensitive file names, or directly in the repository by using the Repository Browser.
However, a file name case change can happen on a case-insensitive operating system, e.g. because of defect software tools, etc. SmartSVN detects such invalid changes and puts the file into a case-changed file state, see Rare Primary File States. Fix now changes the file name case back to its original form as found within the pristine copy, resolving this problem.
翻译：大小写修改文件
SVN储存库和工作副本通常是区分大小写的。这可能会在处理不区分大小写的操作系统时造成问题，比如Microsoft Windows或苹果Mac OS上的一些文件系统，并更改文件名的情况(大写到小写等)。由于SVN的工作拷贝格式和原始副本，在技术上不可能处理这样的文件名称更改。
一种解决方案是，通过在操作系统上执行文件名称case更改来避免这种情况，该操作系统支持区分大小写的文件名，或者直接在存储库中使用存储库浏览器。
但是，在不区分大小写的操作系统上可能会发生文件名称的更改，例如由于缺陷软件工具等。SmartSVN检测到这种无效的更改，并将文件放入一个更改过的文件状态中，见罕见的主文件状态。Fix现在将文件名称实例更改为原始副本中的原始表单，以解决此问题。
