fugitive.vim gives you a nifty helper:
:Gread that allows you to checkout to the previous version of the file.
Supposed that you committed some changes, but after a while you decided to get rid of those changes. As
% represent the current file in fugitive.vim, to get back to the previous version, you only have to run:
Actually you can do something similar in any terminal window:
git checkout head~42 path/to/the/file.rb
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