fix(tools): read the select_tests changed-file list as UTF-8 with a byte order mark

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

tools/select_tests.py

@@ -237,7 +237,7 @@ def main():
         print("full run: no test graph")
         return 0
     graph = json.loads(Path(args.graph).read_text(encoding="utf-8"))
-    changed = [line.strip() for line in Path(args.changed).read_text(encoding="utf-8").splitlines() if line.strip()]
+    changed = [line.strip() for line in Path(args.changed).read_text(encoding="utf-8-sig").splitlines() if line.strip()]
     picked, full = select(graph, changed)
     if picked is None:
         print(f"full run: {', '.join(full[:5])}")

tools/tests/test_select_tests.py

@@ -101,6 +101,13 @@ class SelectTests(unittest.TestCase):
                 self.assertIsNone(selected)
                 self.assertIn(changed, output)
 
+    def test_changed_list_with_a_byte_order_mark_and_crlf_keeps_its_first_path(self):
+        listed = self.build / "changed bom.txt"
+        listed.write_bytes(b"\xef\xbb\xbfCMakeLists.txt\r\nalpha/alpha.h\r\n")
+        output = self.tool("select", self.build, self.graph, listed)
+        self.assertIn("CMakeLists.txt", output)
+        self.assertFalse((self.build / "select.tests").exists())
+
     def test_missing_graph_runs_everything(self):
         self.assertIsNone(self.select("alpha/alpha.h", graph=self.build / "missing.json")[1])