If you have not installed a newer version of Git on your Mac, start with this. You can download here: http://git-scm.com/download
After installing it, you must specify git-completion.sh and git-prompt.sh from ~/.profile (or ~ / .bashrc, if any):
source /usr/local/git/contrib/completion/git-completion.bash source /usr/local/git/contrib/completion/git-prompt.sh
This should fix the __git_ps1 error.
I'm not a hack, but the rbenv error comes from the fact that the dotfiles setting that you use is trying to set the default Ruby version to "1.9.3-p194". The rbenv tool is designed to create several different versions of Ruby, but you need to install them first. In your case, I think you need to run this:
rbenv install 1.9.3-p194
After that, the version will be available and you will no longer see a warning.
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