Merge pull request juju#18216 from Aflynn50/fix-local-charm-git-issue

juju#18216

Git needed to have user details to commit, this sets the user. I hadn't realised this before because it worked with my own local git user settings.

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<!-- Why this change is needed and what it does. -->

## Checklist

<!-- If an item is not applicable, use `~strikethrough~`. -->

- [x] Code style: imports ordered, good names, simple structure, etc
- [x] Comments saying why design decisions were made
- [x] Go unit tests, with comments saying what you're testing
- [x] [Integration tests](https://github.com/juju/juju/tree/main/tests), with comments saying what you're testing
- [ ] [doc.go](https://discourse.charmhub.io/t/readme-in-packages/451) added or updated in changed packages

## QA steps

<!-- Describe steps to verify that the change works. -->
```
./main.sh -v cli
```

tests/suites/cli/local_charms.sh

@@ -14,8 +14,7 @@ run_deploy_local_charm_revision() {
 	cd "${TMP}/ubuntu-plus" || exit 1
 
 	# Initialise a git repo to check the commit SHA is used as the charm version.
-	git init
-	git add . && git commit -m "commit everything"
+	create_local_git_and_commit_all
 	SHA_OF_UBUNTU_PLUS=\"$(git describe --dirty --always)\"
 
 	# Deploy from directory.
@@ -100,8 +99,7 @@ run_deploy_local_charm_revision_relative_path() {
 	cd "${TMP}/ubuntu-plus" || exit 1
 
 	# Initialise a git repo and commit everything so that commit SHA is used as the charm version.
-	git init
-	git add . && git commit -m "commit everything"
+	create_local_git_and_commit_all
 	SHA_OF_UBUNTU_PLUS=\"$(git describe --dirty --always)\"
 
 	# Create git directory outside the charm directory
@@ -149,8 +147,7 @@ run_deploy_local_charm_revision_invalid_git() {
 	cd "${TMP_CHARM_GIT}/ubuntu-plus" || exit 1
 
 	# Initialise a git repo and commit everything so that commit SHA is used as the charm version.
-	git init
-	git add . && git commit -m "commit everything"
+	create_local_git_and_commit_all
 	SHA_OF_UBUNTU_PLUS=\"$(git describe --dirty --always)\"
 
 	WANTED_CHARM_SHA=\"$(git describe --dirty --always)\"
@@ -183,6 +180,15 @@ create_local_git_folder() {
 	git commit -am "rand_file"
 }
 
+create_local_git_and_commit_all() {
+	git init .
+	if [ -z "$(git config --global user.email)" ]; then
+		git config --global user.email "[email protected]"
+		git config --global user.name "John Doe"
+	fi
+	git add . && git commit -m "commit everything"
+}
+
 test_local_charms() {
 	if [ "$(skip 'test_local_charms')" ]; then
 		echo "==> TEST SKIPPED: deploy local charm tests"