Update changelog generation for release tag

Signed-off-by: Michael Marchetti <mmarchetti@sandvine.com>

tools/generatechangelog-pipeline.sh

@@ -2,8 +2,17 @@
 
 REPO_NAME=$(basename $(git config --get remote.origin.url) | cut -d'.' -f1)
 # get the latest tag
-TAG_END="HEAD"
 TAG_START=$(git tag | sort -Vr | head -1)
+
+head_tag_diff=$(git rev-list $TAG_START ^HEAD |wc -l)
+if  [ $head_tag_diff -eq 0 ]; then
+    # HEAD and latest tag intersect. Instead try and find a previous tag and use that as the start diff
+    TAG_END=$TAG_START
+    TAG_START=$(git tag | sort -Vr | head -2 | sort -V | head -1)
+else
+    TAG_END="HEAD"
+fi
+
 git pull --tags origin master &> /dev/null
 echo "<h1>$REPO_NAME Changelog</h1>"
 echo "<h2>tag: ${TAG_START} -> ${TAG_END}</h2>"