feat(three-stage-scan): add aliased-sink mutation the regex scan misses

benchmarks/fixtures/mutation-python/app.py

@@ -0,0 +1,13 @@
+"""Mutation of os.system: the callable is aliased before use so a same-line regex misses it."""
+import os
+
+from flask import Flask, request
+
+app = Flask(__name__)
+run_cmd = os.system
+
+
+@app.get("/ping")
+def ping():
+    host = request.args["host"]
+    return run_cmd("ping -c 1 " + host)  # CWE-78 mutation: os.system aliased before the call