Cancel calls on unexpected exceptions (3.12.x branch)

Closes: https://github.com/square/okhttp/issues/5151

okhttp-tests/src/test/java/okhttp3/InterceptorTest.java

@@ -553,13 +553,14 @@ public final class InterceptorTest {
   }
 
   /**
-   * When an interceptor throws an unexpected exception, asynchronous callers are left hanging. The
+   * When an interceptor throws an unexpected exception, asynchronous calls are canceled. The
    * exception goes to the uncaught exception handler.
    */
   private void interceptorThrowsRuntimeExceptionAsynchronous(boolean network) throws Exception {
+    final RuntimeException boom = new RuntimeException("boom!");
     addInterceptor(network, new Interceptor() {
       @Override public Response intercept(Chain chain) throws IOException {
-        throw new RuntimeException("boom!");
+        throw boom;
       }
     });
 
@@ -571,9 +572,13 @@ public final class InterceptorTest {
     Request request = new Request.Builder()
         .url(server.url("/"))
         .build();
-    client.newCall(request).enqueue(callback);
-
-    assertEquals("boom!", executor.takeException().getMessage());
+    Call call = client.newCall(request);
+    call.enqueue(callback);
+    RecordedResponse recordedResponse = callback.await(server.url("/"));
+    assertEquals("canceled due to java.lang.RuntimeException: boom!",
+        recordedResponse.failure.getMessage());
+    assertTrue(call.isCanceled());
+    assertSame(boom, executor.takeException());
   }
 
   @Test public void applicationInterceptorReturnsNull() throws Exception {

okhttp/src/main/java/okhttp3/RealCall.java

@@ -210,6 +210,13 @@ final class RealCall implements Call {
           eventListener.callFailed(RealCall.this, e);
           responseCallback.onFailure(RealCall.this, e);
         }
+      } catch (Throwable t) {
+        cancel();
+        if (!signalledCallback) {
+          IOException canceledException = new IOException("canceled due to " + t);
+          responseCallback.onFailure(RealCall.this, canceledException);
+        }
+        throw t;
       } finally {
         client.dispatcher().finished(this);
       }