fix(retry): when # of retries is smaller than one

spec/operators/retry-spec.ts

@@ -326,4 +326,17 @@ describe('retry operator', () => {
 
     expect(sideEffects).to.deep.equal([0, 1, 2]);
   });
+
+  it('should not alter the source when the number of retries is smaller than 1', () => {
+    const source = cold('--1-2-3-#');
+    const subs =       ['^       !'];
+
+    const expected =    '--1-2-3-#';
+    const unsub =       '         !';
+
+    const result = source.pipe(retry(0));
+
+    expectObservable(result, unsub).toBe(expected);
+    expectSubscriptions(source.subscriptions).toBe(subs);
+  })
 });

src/internal/operators/retry.ts

@@ -1,8 +1,8 @@
 import { MonoTypeOperatorFunction } from '../types';
 import { operate } from '../util/lift';
 import { Subscription } from '../Subscription';
-import { EMPTY } from '../observable/empty';
 import { OperatorSubscriber } from './OperatorSubscriber';
+import { identity } from '../util/identity';
 
 export interface RetryConfig {
   count: number;
@@ -69,7 +69,7 @@ export function retry<T>(configOrCount: number | RetryConfig = Infinity): MonoTy
   const { count, resetOnSuccess = false } = config;
 
   return count <= 0
-    ? () => EMPTY
+    ? identity
     : operate((source, subscriber) => {
         let soFar = 0;
         let innerSub: Subscription | null;