rubygems/rubygems — pull request #571 by mpapis (2013-06-09 21:49:27+00:00)
Title: fix detecting yaml parsing errors for psych, add the parsing message

follow up from https://github.com/wayneeseguin/rvm/issues/1955

- fixes detecting parsing errors when `Psych` is used
- adds the parsing error to the warning so it's easier to locate the problem

please also port this to `rubygems` 2.0