patch 9.2.0553: runtime(netrw): netrw rejects hostnames containing _

Problem:  runtime(netrw): netrw rejects hostnames containing _
          (lilydjwg)
Solution: Relax the restriction and allow the underscore

fixes: #20344

Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/pack/dist/opt/netrw/autoload/netrw.vim

@@ -1,7 +1,7 @@
 " Creator:    Charles E Campbell
 " Previous Maintainer: Luca Saccarola <github.e41mv@aleeas.com>
 " Maintainer: This runtime file is looking for a new maintainer.
-" Last Change: 2026 May 17
+" Last Change: 2026 May 28
 " Copyright:  Copyright (C) 2016 Charles E. Campbell {{{1
 "             Permission is hereby granted to use and distribute this code,
 "             with or without modifications, provided that this copyright
@@ -2581,8 +2581,8 @@ function s:NetrwValidateHostname(hostname)
   " Username:
   let user_pat = '\%([a-zA-Z0-9._-]\+@\)\?'
   " Hostname: 1-64 chars, alphanumeric/dots/hyphens.
-  " No underscores. No leading/trailing dots/hyphens.
-  let host_pat = '[a-zA-Z0-9]\%([-a-zA-Z0-9.]\{0,62}[a-zA-Z0-9]\)\?'
+  " No leading/trailing dots/hyphens.
+  let host_pat = '[a-zA-Z0-9_]\%([-a-zA-Z0-9._]\{0,62}[a-zA-Z0-9_]\)\?'
   " Port: 16 bit unsigned integer
   let port_pat = '\%(:\d\{1,5\}\)\?$'
 

src/testdir/test_plugin_netrw.vim

@@ -610,6 +610,7 @@ endfunc
 func Test_netrw_hostname()
   let valid_hostnames = [
   \   'localhost',
+  \   '_gateway',
   \   '127.0.0.1',
   \   '::1',
   \   '0:0:0:0:0:0:0:1',

src/version.c

@@ -729,6 +729,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    553,
 /**/
     552,
 /**/