Temporarily switch working copy to a specific Git commit

If you are at a certain branch mybranch, just go ahead and git checkout commit_hash. Then you can return to your branch by git checkout mybranch. I had the same game bisecting a bug today :) Also, you should know about git bisect.

In addition to the other answers here showing you how to git checkout <the-hash-you-want> it's worth knowing you can switch back to where you were using:

git checkout @{-1}

This is often more convenient than:

git checkout what-was-that-original-branch-called-again-question-mark

As you might anticipate, git checkout @{-2} will take you back to the branch you were at two git checkouts ago, and similarly for other numbers. If you can remember where you were for bigger numbers, you should get some kind of medal for that.

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Sadly for productivity, git checkout @{1} does not take you to the branch you will be on in future, which is a shame.

First, use git log to see the log, pick the commit you want, note down the sha1 hash that is used to identify the commit. Next, run git checkout hash. After you are done, git checkout original_branch. This has the advantage of not moving the HEAD, it simply switches the working copy to a specific commit.