Python: Expand starargs_only test

Author: RasmusWL

python/ql/lib/semmle/python/dataflow/new/internal/DataFlowDispatch.qll

@@ -1085,6 +1085,7 @@ predicate normalCallArg(CallNode call, Node arg, ArgumentPosition apos) {
     arg.asCfgNode() = call.getArgByName(name)
   )
   or
+  // the first `*args`
   exists(int index |
     apos.isStarArgs(index) and
     arg.asCfgNode() = call.getStarArg() and

python/ql/test/experimental/dataflow/coverage/argumentPassing.py

@@ -217,6 +217,10 @@ def test_only_starargs():
     args = (arg1, arg2, "safe") # $ arg1 arg2 func=starargs_only
     starargs_only(*args)
 
+    args = (arg1, arg2) # $ arg1 arg2 func=starargs_only
+    more_args = (arg3, arg4)
+    starargs_only(*args, *more_args)
+
 
 def starargs_mixed(a, *args):
     SINK1(a)