pull and merge, leaving `frotz.c` and `filfre.c`
    changes still in the working tree.

Undo a commit and redo::
+
------------
$ git commit ...
$ git reset --soft HEAD^      <1>
$ edit                        <2>
$ git commit -a -c ORIG_HEAD  <3>
------------
+
<1> This is most often done when you remembered what you
    just committed is incomplete, or you misspelled your commit
    message, or both.  Leaves working tree as it was before "reset".
<2> Make corrections to working tree files.
<3> "reset" copies the old head to `.git/ORIG_HEAD`; redo the
    commit by starting with its log message.  If you do not need to
    edit the message further, you can give `-C` option instead.
+
See also the `--amend` option to linkgit:git-commit[1].

Undo a commit, making it a topic branch::
+
------------
$ git branch topic/wip          <1>
$ git reset --hard HEAD~3       <2>
$ git switch topic/wip          <3>
------------
+
<1> You have made some commits, but realize they were premature
    to be in the `master` branch.  You want to continue polishing
    them in a topic branch, so create `topic/wip` branch off of the
    current `HEAD`.
<2> Rewind the master branch to get rid of those three commits.
<3> Switch to `topic/wip` branch and keep working.

Undo commits permanently::
+
------------
$ git commit ...
$ git reset --hard HEAD~3   <1>
------------
+
<1> The last three commits (`HEAD`, `HEAD^`, and `HEAD~2`) were bad
    and you do not want to ever see them again.  Do *not* do this if
    you have already given these commits to somebody else.  (See the
    "RECOVERING FROM UPSTREAM REBASE" section in linkgit:git-rebase[1]
    for the implications of doing so.)

Undo a merge or pull::
+
------------
$ git pull                         <1>
Auto-merging nitfol
CONFLICT (content): Merge conflict in nitfol
Automatic merge failed; fix conflicts and then commit the result.
$ git reset --hard                 <2>
$ git pull . topic/branch          <3>
Updating from 41223... to 13134...
Fast-forward
$ git reset --hard ORIG_HEAD       <4>
------------
+
<1> Try to update from the upstream resulted in a lot of
    conflicts; you were not ready to spend a lot of time merging
    right now, so you decide to do that later.
<2> "pull" has not made merge commit, so `git reset --hard`
    which is a synonym for `git reset --hard HEAD` clears the mess
    from the index file and the working tree.
<3> Merge a topic branch into the current branch, which resulted
    in a fast-forward.
<4> But you decided that the topic branch is not ready for public
    consumption yet.  "pull" or "merge" always leaves the original
    tip of the current branch in `ORIG_HEAD`, so resetting hard to it
    brings your index file and the working tree back to that state,
    and resets the tip of the branch to that commit.

Undo a merge or pull inside a dirty working tree::
+
------------
$ git pull                         <1>
Auto-merging nitfol
Merge made by recursive.
 nitfol                |   20 +++++----
 ...
$ git reset --merge ORIG_HEAD      <2>
------------
+
<1> Even if you may have local modifications in your
    working tree, you can safely say `git pull` when you know
    that the change in the other branch does not overlap with
    them.
<2> After inspecting the result of the merge, you may find
    that the change in the other branch is unsatisfactory.  Running
    `git reset --hard ORIG_HEAD` will let you go back to where you
    were, but it will discard your local changes, which you do not
    want.  `git reset --merge` keeps your local changes.


Interrupted workflow::
+
Suppose you are interrupted by an urgent fix request while you
are in the middle of a large change.  The files in your
working tree are not in any shape to be committed yet, but you
need to get to the other branch for a quick bugfix.
+
------------
$ git switch feature  ;# you were working in "feature" branch and
$ work work work      ;# got interrupted
$ git commit -a -m "snapshot WIP"