Changelog generator fixes

There were several problems that this fixes:
- shallow fetch broke merging to release branch
- bad changelog was only outputting error msg (not exiting)
- latest version being on first line deleted itself and broke the
  changelog updates

This also has manual fixes to the changelog to bring it up to date.

Co-authored-by: Micah Jerome Ellison <micah.jerome.ellison@gmail.com>

.github/workflows/changelog.yaml

@@ -85,6 +85,13 @@ jobs:
             exit 1
           fi
 
+          if [[ $tagline == 1 ]]; then
+            echo "::error::Something is wrong."
+            echo "::error::The latest release ${SINCE_TAG} is the first line in the changelog,"
+            echo "::error::but the h1 '# Changelog' should always be the first line."
+            exit 1
+          fi
+
           sed -i "1,$(expr $tagline - 1)d" "$FILENAME"
           # delete generated line (or it will be added multiple times)
           sed -i '/This Changelog was automatically generated by/d' "$FILENAME"
@@ -124,6 +131,7 @@ jobs:
           git diff
           if [[ $(grep -c '^# Changelog$' "$FILENAME") != 1 ]]; then
             echo '::error::Something is wrong with the changelog.'
+            exit 1
           fi
           SOMETHING_CHANGED=false
           git diff --exit-code || SOMETHING_CHANGED=true
@@ -142,6 +150,7 @@ jobs:
       - name: Merge to Release branch
         if: env.FULL_RELEASE == 'true'
         run: |
+          git fetch --unshallow origin
           git checkout release
           git merge --ff-only $BRANCH
           git push origin release