Ticket #22287: 22287.diff

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

@@ -496 +496 @@
                 // Assume the requested plugin is the first in the list.
                 $pluginfiles = array_keys( $plugin );
 
+                usort( $pluginfiles, array( $this, '_plugin_info_sort_comparison' ) );
+
                 return $this->result['destination_name'] . '/' . $pluginfiles[0];
         }
 
+        /**
+         * Internal function for comparing paths to sort plugin files in no directory to the top.
+         *
+         * @param  string $plugin_file_a
+         * @param  string $plugin_file_b
+         * @return int
+         */
+        function _plugin_info_sort_comparison( $plugin_file_a, $plugin_file_b ) {
+                return strstr( $plugin_file_a, '/' ) ? 1 : -1;
+        }
+
         /**
          * Deactivates a plugin before it is upgraded.
          *