Jenkins can''t connect to Git repository

I'm trying to set up Jenkins referencing a Git repository. However I get this strange error

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Any idea what is wrong. The repository works fine on my team mates computers.

Solution

Even though your "mates" have access to the Goatic/hangman git repository, Jenkins does not as it is running under a different user. You can add credentials from the Jenkins admin screen by doing Manage Jenkins -> Configure System

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Have a look at this SO post for more information.