propagate the error to redirectTask rather than simply cancel()

Author: gregcotten

Sources/AsyncHTTPClient/RequestBag.swift

@@ -362,7 +362,7 @@ final class RequestBag<Delegate: HTTPClientResponseDelegate> {
 
         self.executeFailAction0(action)
 
-        self.redirectTask?.cancel()
+        self.redirectTask?.fail(reason: error)
     }
 
     private func executeFailAction0(_ action: RequestBag<Delegate>.StateMachine.FailAction) {

Tests/AsyncHTTPClientTests/HTTPClientTests.swift

@@ -4159,6 +4159,35 @@ final class HTTPClientTests: XCTestCaseHTTPClientTestsBaseClass {
         }
     }
 
+    func testFailingRequestAfterRedirect() throws {
+        let request = try Request(
+            url: self.defaultHTTPBinURLPrefix + "redirect/target",
+            method: .GET,
+            headers: ["X-Target-Redirect-URL": self.defaultHTTPBinURLPrefix + "wait"],
+            body: nil
+        )
+
+        class FailAfterRedirect: HTTPClientResponseDelegate {
+            init() {}
+            func didFinishRequest(task: AsyncHTTPClient.HTTPClient.Task<Void>) throws {}
+        }
+
+        let task = defaultClient.execute(request: request, delegate: FailAfterRedirect(), deadline: .now() + .seconds(1))
+
+        // there is currently no HTTPClientResponseDelegate method to ensure the redirect occurs before we fail, so we just sleep for 500ms
+        Thread.sleep(forTimeInterval: 0.5)
+
+        struct TestError: Error {}
+
+        task.fail(reason: TestError())
+
+        XCTAssertThrowsError(try task.wait()) { error in
+            guard error is TestError else {
+                return XCTFail("Should fail with TestError")
+            }
+        }
+    }
+
     func testCancelingHTTP1RequestAfterHeaderSend() throws {
         var request = try HTTPClient.Request(url: self.defaultHTTPBin.baseURL + "/wait", method: .POST)
         // non-empty body is important