commit: warn when a new commit is dated before its parent

[srinivas1591]

What does this PR do?
This PR adds a helpful warning if you try to make a new commit with a date that is older than its parent commit.

Why is this needed?
Git just uses whatever time your computer's clock says when creating a commit. If your system clock is incorrect, you might accidentally create a commit dated in the past.

This causes problems because commands like git log --since assume that commit dates always move forward. If a date goes backward in history, those commands can get confused and accidentally hide commits from the log.

What is fixed?
We added a new configuration setting called advice.clockSkew. Now, Git will warn you right away if your computer's clock seems to be wrong when you are making a new commit. This gives you a chance to fix your computer's time before you accidentally push out-of-order dates!

[gitgitgadget]

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[gitgitgadget]

There are issues in commit ad2f822:
commit: warn when a new commit is dated before its parent

• Commit not signed off
• Lines in the body of the commit messages should be wrapped between 60 and 76 characters.
  Indented lines, and lines without whitespace, are exempt

[gitgitgadget]

There is an issue in commit c68506b:
commit: warn when a new commit is dated before its parent

• Lines in the body of the commit messages should be wrapped between 60 and 76 characters.
  Indented lines, and lines without whitespace, are exempt

[dscho]

@srinivas1591 could you please use your real name in the Signed-off-by line and in your author information? The Git project insists on that. You can fix it by configuring user.name, then git commit --amend --reset-author --signoff (deleting the superseded Signed-off-by line), and force-pushing.

[dscho]

/allow

[gitgitgadget]

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