Upload: Run the final file name collision test in `wp_unique_filename()` for each existing file + 1.

Props pbiron.
See #48975.

Built from https://develop.svn.wordpress.org/trunk@46976


git-svn-id: http://core.svn.wordpress.org/trunk@46776 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -2492,7 +2492,7 @@ function wp_unique_filename( $dir, $filename, $unique_filename_callback = null )
 				// Ensure this never goes into infinite loop
 				// as it uses pathinfo() and regex in the check but string replacement for the changes.
 				$count = count( $files );
-				$i     = 1;
+				$i     = 0;
 
 				while ( $i <= $count && _wp_check_existing_file_names( $filename, $files ) ) {
 					$new_number = (int) $number + 1;

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.4-alpha-46974';
+$wp_version = '5.4-alpha-46976';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.