Make prevous version optional in source_changelog.bash

The latest tagged version is used as the default.

Signed-off-by: Addisu Z. Taddese <[email protected]>

source-repo-scripts/source_changelog.bash

@@ -1,10 +1,18 @@
 #!/bin/bash
+# Generates a list of changes since the last tagged version. 
+#   bash source_changelog.bash
+#
+# Optionally, the previous version can be provided
 # bash source_changelog.bash <PREV_VER>
-
-PREV_VER=$1
+#
+#   E.g.
+#   bash source_changelog.bash 3.0.0
 
 git fetch --tags
 
+PREV_VER=${1:-$(git describe --tags --abbrev=0 | sed 's/.*_//')}
+echo "Changes since $PREV_VER"
+
 ORIGIN_URL=$(git remote get-url origin)
 REPO=$(basename ${ORIGIN_URL%.git})
 
@@ -14,7 +22,7 @@ PREV_TAG=$(git tag | grep "_${PREV_VER}$")
 # Compare current branch to PREV_TAG
 BRANCH=$(git rev-parse --abbrev-ref HEAD)
 
-COMMITS=$(git log ${BRANCH}...${PREV_TAG}  --pretty=format:"%h")
+COMMITS=$(git log ${BRANCH}...${PREV_TAG} --no-merges --pretty=format:"%h")
 
 for COMMIT in $COMMITS
 do