Make submodule-sync always try update cudf-pins [skip ci]

ci/submodule-sync.sh

@@ -57,17 +57,19 @@ if [ -n "$CUDF_TAG" ]; then
 else
   git submodule update --remote --merge
 fi
+
+cudf_pins_only=false
 cudf_sha=$(git -C thirdparty/cudf rev-parse HEAD)
 if [[ "${cudf_sha}" == "${cudf_prev_sha}" ]]; then
-  echo "Submodule is up to date."
-  exit 0
+  echo "cuDF submodule is up to date. Try update cudf-pins..."
+  cudf_pins_only=true
+else
+  echo "Try update cudf submodule to ${cudf_sha}..."
+  git add .
+  git commit -s -m "Update submodule cudf to ${cudf_sha}"
 fi
 
-echo "Try update cudf submodule to ${cudf_sha}..."
-git add .
-
-echo "Test against ${cudf_sha}..."
-
+echo "Build libcudf only to update pinned versions..."
 MVN="mvn -Dmaven.wagon.http.retryHandler.count=3 -B"
 set +e
 # Don't do a full build. Just try to update/build CUDF with no patches on top of it.
@@ -101,9 +103,17 @@ sed -i -e 's/4\.0\.1\.0/3.0.6/' \
 # the updated versions.json generated by the build
 echo "Update cudf submodule to ${cudf_sha} with updated pinned versions"
 git add .
-git diff-index --quiet HEAD || git commit -s -m "Update submodule cudf to ${cudf_sha}"
+if ! git diff-index --quiet HEAD; then
+  # We perform a squash merge for submodule-sync commits
+  git commit -s -m "Update pinned versions for cudf ${cudf_sha}"
+elif ${cudf_pins_only}; then
+  echo "No changes to commit. Exit early..."
+  exit 0
+fi
+
 sha=$(git rev-parse HEAD)
 
+echo "Test against ${cudf_sha}..."
 set +e
 # now build and test everything with the patches in place
 ${MVN} clean verify ${MVN_MIRROR} \