Invalid `Podfile` file: undefined method `exists?‘ for File:Class

flutter 2.0.5

cocopod 1.11.1  不报错

升级到1.12.1 就Invalid `Podfile` file: undefined method `exists?' for File:Class

修改 fluttersdk 目录下

packages/flutter_tools/bin/podhelper.rb
return [] unless File.exists? file_path
改成：
return [] unless File.exist? file_path

这样pod install 正常