Ticket #30945: 30945.1.diff

src/wp-admin/includes/class-wp-upgrader.php

@@ -264 +264 @@
                 }
 
                 //We need a working directory
-                $working_dir = $upgrade_folder . basename($package, '.zip');
+                $dirname = basename( $package );
+                if ( in_array( strtolower( substr( $dirname, -4 ) ), array( '.zip', '.tmp' ) ) ) {
+                        $dirname = substr( $dirname, 0, ( strlen( $dirname ) - 4 ) );
+                }
+                $working_dir = $upgrade_folder . $dirname;
 
                 // Clean up working directory
                 if ( $wp_filesystem->is_dir($working_dir) )