Incorrect number of commits before head for shown output.

[cgeroux]

This pull request Closes #963

As I followed along, the git diff HEAD~3 on episode 5 references a commit back one commit further than my history. This leads to the output fatal: ambiguous argument 'HEAD~3': unknown revision or path not in the working tree..

It is possible if a previous aside (the directories callout) is followed that this will not generate unknown revision issue. With this change with the directories callout skipped it will produce output that is consistent with that shown in the lesson. If the directories callout is followed, it will produce inconsistent output, however, it will not produce the "fatal" error as it does now in the situation where the "directories" callout isn't followed.

A competing solution would be to make the "directories" callout not a callout, but part of the flow of the workshop. However, in general it does seem to me that the "directories" callout really should be a callout and isn't critical to the overall flow of the lesson.

[github-actions]

🆗 Pre-flight checks passed 😃

This pull request has been checked and contains no modified workflow files, spoofing, or invalid commits.

It should be safe to Approve and Run the workflows that need maintainer approval.

[kekoziar]

@cgeroux will you verify which commits you entered (git log)? There should be four at that point.

[cgeroux]

I only have three:

`$ git log
commit aa9678528ef6ae74ccddd2ca1955a1f4ea2ffb79 (HEAD -> main)
Author: Chris Geroux [email protected]
Date: Tue Apr 30 11:05:45 2024 -0300

Discuss concerns about Mars' climate for Mummy

commit 745ca038a4d6adc760095b46f40004730efcf0a5
Author: Chris Geroux [email protected]
Date: Tue Apr 30 10:52:02 2024 -0300

Add concerns about effects of Mars' moons on Wolfman

commit 2ea1847fc9f697d706b571f32337313aece2ef55
Author: Chris Geroux [email protected]
Date: Tue Apr 30 10:37:29 2024 -0300

Start notes on Mars as a base

`

[cgeroux]

If I did an extra commit, as mentioned in the "Directories" callout:

git commit -m "Add some initial thoughts on spaceships"

I would then have four.

[cgeroux]

Another possibility to have 4 commits would be from the commit in the "COMMITTING MULTIPLE FILES" exercise.

$ git commit -m "Write plans to start a base on Venus"

[martinosorb]

Moving from HEAD~3 to HEAD~2 seems sufficiently harmless to me. @swcarpentry/git-novice-maintainers shall we merge?

[erinmgraham]

I'm happy to merge.