Merge pull request #8960 from hashicorp/td-prepare-changelog-update

scripts/prepare_changelog: Update git log to only display PR merged commits

scripts/prepare_changelog.sh

@@ -30,7 +30,7 @@ fi
 
 get_prs(){
     # git log v0.10.2...c3861d167533fb797b0fae0c380806625712e5f7 |
-    git log HEAD...${LAST_RELEASE} |
+    git log HEAD...${LAST_RELEASE} --first-parent --oneline --grep="Merge pull request #[0-9]\+" --grep="(#[0-9]\+)$" |
     grep -o "#\([0-9]\+\)" | awk -F\# '{print $2}' | while read line
     do
         grep -q "GH-${line}" CHANGELOG.md