Index: src/wp-includes/cron.php
===================================================================
--- src/wp-includes/cron.php	(revision 26778)
+++ src/wp-includes/cron.php	(working copy)
@@ -168,8 +168,15 @@
 		$args = array_slice( func_get_args(), 1 );
 	}
 
-	while ( $timestamp = wp_next_scheduled( $hook, $args ) )
-		wp_unschedule_event( $timestamp, $hook, $args );
+	$crons = _get_cron_array();
+	if ( empty( $crons ) )
+		return;
+	$key = md5( serialize( $args ) );
+	foreach ( $crons as $timestamp => $cron ) {
+		if ( isset( $cron[$hook][$key] ) ) {
+			wp_unschedule_event( $timestamp, $hook, $args );
+		}
+	}
 }
 
 /**