patchlevel on Gemfile on mac os x broken in latest version

I think this commit:

https://github.com/wayneeseguin/rvm/commit/0faf9a801967df00d1b0b97e385d8cde7b94628f

Broke 'patchlevel' Gemfile support. Doing:

$ rvm get 1.26.2
$ cd my_dir
ruby-1.9.3-p551 is not installed.
To install do: 'rvm install ruby-1.9.3-p551'

Then upgrading to 1.26.3:

$ rvm get 1.26.3
...
$ cd ../jnsq_server/
Unknown ruby string (do not know how to handle): ruby-1.9.3,pachlevel:551.
ruby-1.9.3,pachlevel:551 is not installed.
To install do: 'rvm install ruby-1.9.3,pachlevel:551'

Note it's stripping the 't' from patchfile. The Gemfile line is:

ruby '1.9.3', patchlevel: '551'

I'm pretty sure the issue is the sed on mac os x does not support tab characters like '\t'. I'd submit a fix but I'm not sure what a good cross platform one is on off the top of my head.