Ticket #59375: 59375.diff

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

@@ -544 +544 @@
                 }
 
                 // Assume the requested plugin is the first in the list.
-                $pluginfiles = array_keys( $plugin );
+                $pluginfile = array_keys( $plugin )[0];
+
+                if ( false !== strpos( $pluginfile, '/' ) ) {
+                        // Prefer first top-level file to remain consistent with
+                        // get_plugins() default behavior with WP_PLUGIN_DIR.
+                        foreach ( $plugin as $file => &$data ) {
+                                if ( false === strpos( $file, '/' ) ) {
+                                        $pluginfile = $file;
+                                }
+                        }
+                }
 
-                return $this->result['destination_name'] . '/' . $pluginfiles[0];
+                return $this->result['destination_name'] . '/' . $pluginfile;
         }
 
         /**