Update found value to true after set() in memcache.

object-cache.php

@@ -491,6 +491,9 @@ function set( $id, $data, $group = 'default', $expire = 0 ) {
 		$mc     =& $this->get_mc( $group );
 		$result = $mc->set( $key, $data, false, $expire );
 
+		// Update the found cache value with the result of the set in memcache.
+		$this->cache[ $key ][ 'found' ] = $result;
+
 		++$this->stats[ 'set' ];
 		$this->group_ops[$group][] = "set $id";
 

tests/test-object-cache.php

@@ -769,20 +769,20 @@ public function test_replace_can_be_performed_per_group(): void {
 
 	public function test_set_returns_true_if_added_successfully(): void {
 		// String.
-		$added_string = $this->object_cache->set( 'foo1', 'data' );
+		$set_string = $this->object_cache->set( 'foo1', 'data' );
 
-		$this->assertTrue( $added_string );
+		$this->assertTrue( $set_string );
 
 		// Array.
-		$added_arr = $this->object_cache->set( 'foo2', [ 'data' ] );
+		$set_arr = $this->object_cache->set( 'foo2', [ 'data' ] );
 
-		$this->assertTrue( $added_arr );
+		$this->assertTrue( $set_arr );
 
 		// Object.
 		$data = new StdClass();
-		$added_obj = $this->object_cache->set( 'foo3', $data );
+		$set_obj = $this->object_cache->set( 'foo3', $data );
 
-		$this->assertTrue( $added_obj );
+		$this->assertTrue( $set_obj );
 	}
 
 	public function test_set_returns_false_if_cached_value_of_checkthedatabaseplease(): void {
@@ -804,7 +804,7 @@ public function test_set_caches_data_locally(): void {
 
 		$expected = [
 			'value' => 'data',
-			'found' => false,
+			'found' => true,
 		];
 
 		$this->assertEquals( $expected, $this->object_cache->cache[ $key ] );
@@ -826,6 +826,27 @@ public function test_set_can_be_performed_per_group(): void {
 		$this->object_cache->set( 'foo1', 'data2', 'group2' );
 		$this->assertEquals( 'data2', $this->object_cache->get( 'foo1', 'group2' ) );
 	}
+
+	public function test_set_updated_found_status_with_memcache_result(): void {
+		// Need this to ensure cache is set witout going to memcache.
+		$group = 'do-not-persist-me';
+		$this->object_cache->add_non_persistent_groups( [ $group ] );
+
+		$this->object_cache->set( 'foo', 'data', $group );
+		$key = $this->object_cache->key( 'foo', $group );
+
+		// Check it's false until we use memcache.
+		$this->assertFalse( $this->object_cache->cache[ $key ][ 'found' ] );
+
+		// Remove non-persistent group.
+		$this->object_cache->no_mc_groups = [];
+
+		// Re-set.
+		$this->object_cache->set( 'foo', 'data', $group );
+
+		// Cached found value should now be true.
+		$this->assertTrue( $this->object_cache->cache[ $key ][ 'found' ] );
+	}
 
 	// Tests for switch_to_blog.