new capacity bits (#67)

tests/fixtures/header_injection/python/unsafe_subscript_set.py

@@ -0,0 +1,13 @@
+# Unsafe: tainted request value flows into the bare-subscript header set
+# `response.headers["X-Forwarded-By"] = lang`.  The LHS-subscript
+# classification path matches `response.headers` / `resp.headers` as a
+# HEADER_INJECTION sink so this form fires alongside the explicit
+# `headers.add` / `set_cookie` method-call shapes.
+from flask import request, make_response
+
+
+def handler():
+    lang = request.args.get("lang")
+    response = make_response("ok")
+    response.headers["X-Forwarded-By"] = lang
+    return response