异常处理：
1、svn commit时报svn: Could not use external editor to fetch log message…错误：
错误描述：
svn commit 时报如下错误：
svn: Commit failed (details follow): svn: Could not use external editor to fetch log message; consider setting the $SVN_EDITOR environment variable or using the --message (-m) or --file (-F) options svn: None of the environment variables SVN_EDITOR, VISUAL or EDITOR are set, and no 'editor-cmd' run-time configuration option was found错误原因：
因为安装SVN后SVN_EDITOR这个环境变量没有设置，而svn commit依赖这个变量，一定要设置。
解决方法：
直接在终端输入下面的命令：
export SVN_EDITOR=vim