DO NOT MERGE: Debugging for testExternalEntity failure on CI

Author: kateinoigakukun

Tests/Foundation/TestXMLParser.swift

@@ -209,6 +209,14 @@ class TestXMLParser : XCTestCase {
                 XCTAssertTrue(childParser.parse())
                 super.parserDidStartDocument(childParser)
             }
+            func parser(_ parser: XMLParser, parseErrorOccurred parseError: Error) {
+                print("===== DEBUG(testExternalEntity) =====")
+                print(dump(parseError))
+                print("Stack trace:")
+                for symbol in Thread.callStackSymbols {
+                    print("  - \(symbol)")
+                }
+            }
         }
         try withTemporaryDirectory { dir, _ in
             let greetingDtdPath = dir.appendingPathComponent("greeting.dtd")
@@ -224,6 +232,7 @@ class TestXMLParser : XCTestCase {
             let parser = XMLParser(data: xml.data(using: .utf8)!)
             // Explicitly disable external entity resolving
             parser.externalEntityResolvingPolicy = .never
+            parser.shouldResolveExternalEntities = false
             let delegate = Delegate()
             parser.delegate = delegate
             XCTAssertTrue(parser.parse())