Add include_builtins to usages, fixes #1131.

test/test_api/test_usages.py

@@ -1,3 +1,14 @@
 def test_import_usage(Script):
     s = Script("from .. import foo", line=1, column=18, path="foo.py")
     assert [usage.line for usage in s.usages()] == [1]
+
+
+def test_exclude_builtin_modules(Script):
+    def get(include):
+        return [(d.line, d.column) for d in Script(source, column=8).usages(include_builtins=include)]
+    source = '''import sys\nprint(sys.path)'''
+    places = get(include=True)
+    assert places == [(None, None), (1, 7), (2, 6)]
+
+    places = get(include=False)
+    assert places == [(1, 7), (2, 6)]