fix: make sure source options are passed through (#5241)

The changes to source caching in #5156 introduced a regression where the source options were no longer available to plugins. This PR makes sure the cached source object retains any source options passed along.

src/js/player.js

@@ -1241,7 +1241,7 @@ class Player extends Component {
     }
 
     // update `currentSource` cache always
-    this.cache_.source = {src, type};
+    this.cache_.source = mergeOptions({}, srcObj, {src, type});
 
     const matchingSources = this.cache_.sources.filter((s) => s.src && s.src === src);
     const sourceElSources = [];

test/unit/player.test.js

@@ -1904,3 +1904,17 @@ QUnit.test('disposing a tech that dit NOT set a poster, should keep the poster',
 
   player.dispose();
 });
+
+QUnit.test('source options are retained', function(assert) {
+  const player = TestHelpers.makePlayer();
+
+  const source = {
+    src: 'https://some.url',
+    type: 'someType',
+    sourceOption: 'someOption'
+  };
+
+  player.src(source);
+
+  assert.equal(player.currentSource().sourceOption, 'someOption', 'source option retained');
+});