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[micheus]

you don't have the dgud's repository added to your remote repository list!
If you fetch the origin, you will always updating you local branch with your remote branch - that was not what I suggest you and isn't what that instructions intend to. See: "Updating your master branch with the official one" - the official one is (currently) dgud's fork.

To fix that you need to run this first:
$ git remote add dgud git://github.com/dgud/wings.git

and then you can run:
$ git fetch dgud
$ git reset --hard dgud/master

This way you will be overwriting your local master with the dgud/master (the current 1.5.2).
If you have already done any changes to some lang files, maybe it would be a good idea backup it before.