feat: add upstream merge helper.

scripts/merger/main.py

@@ -0,0 +1,30 @@
+import os
+import sys
+import shutil
+
+
+def main():
+    assert len(sys.argv) == 4, 'invalid options.'
+
+    # without 'mc' suffix.
+    ll_mc_base = sys.argv[1]
+    lf_mc_base = sys.argv[2]
+
+    empty_list = sys.argv[3]
+
+    assert ll_mc_base.endswith('/src/')
+    assert lf_mc_base.endswith('/src/')
+
+    assert os.path.isdir(ll_mc_base)
+    assert os.path.isdir(lf_mc_base)
+    assert os.path.isfile(empty_list)
+
+    with open(empty_list) as file:
+        content = file.read()
+        for empty_file in content.split('\n'):
+            if len(empty_file) > 0:
+                shutil.copyfile(ll_mc_base + empty_file, lf_mc_base + empty_file)
+
+
+if __name__ == '__main__':
+    main()