pass error to retries option

Closes #119

index.js

@@ -56,7 +56,7 @@ function requestAsEventEmitter(opts) {
 		});
 
 		req.once('error', function (err) {
-			var backoff = opts.retries(++retryCount);
+			var backoff = opts.retries(++retryCount, err);
 			if (backoff) {
 				setTimeout(get, backoff, opts);
 				return;

readme.md

@@ -123,7 +123,7 @@ Default: `5`
 
 Number of request retries when network errors happens. Delays between retries counts with function `Math.pow(2, retry) + Math.random() * 100`, where `retry` is attempt number (starts from 0).
 
-Option accepts `function` with `retry` argument that must return delay in milliseconds (`0` return value cancels retry).
+Option accepts `function` with `retry` and `error` arguments. Function must return delay in milliseconds (`0` return value cancels retry).
 
 ##### callback(error, data, response)
 

test/retry.js

@@ -58,6 +58,17 @@ test('falsy value prevent retries', async t => {
 	}
 });
 
+test('falsy value prevent retries', async t => {
+	try {
+		await got(`${s.url}/long`, {timeout: 100, retries: (iter, err) => {
+			t.ok(err);
+			return false;
+		}});
+	} catch (err) {
+		t.ok(err);
+	}
+});
+
 test.after('cleanup', async t => {
 	await s.close();
 });