override-username not applied to consecutively called plugins

Hi,

Probably not exactly a bug, but at least for me undesired behavior: I was playing with the soon-to-be-introduced --override-username option, setting it from within a plugin using a temporary client_config_file at the OPENVPN_PLUGIN_CLIENT_CONNECT step.

What I noticed is that consecutively called plugins are not called with the updated username, but still get the "original" username, even when registered for the OPENVPN_PLUGIN_CLIENT_CONNECT_V2 step and being registered after the username-overriding plugin.

In the context of the plugin, which implements external webauth via OIDC, the original username is basically an empty string and thereby not helpful for that "other" plugin that just records (dis-)connection events.

To Reproduce
Register two plugins and have the first pass the override-username option using a client_config_file. The second plugin will receive the original username in its envp-array

Expected behavior
The second plugin receives the updated username on its OPENVPN_PLUGIN_CLIENT_CONNECT_V2 call.

Version information

• OS: Ubuntu 24.04
• OpenVPN version: v2.7_alpha2/master

Additional Context
I managed get the desired behavior by having openvpn call the override_locked_username function earlier, within multi_client_connect_post:

diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
index a760e071..1cda7188 100644
--- a/src/openvpn/multi.c
+++ b/src/openvpn/multi.c
@@ -1679,6 +1679,10 @@ multi_client_connect_post(struct multi_context *m,
          */
         multi_select_virtual_addr(m, mi);
         multi_set_virtual_addr_env(mi);
+        if (mi->context.options.override_username)
+        {
+            override_locked_username(mi);
+        }
     }
 }

It does work for my scenario, however, I'm not quite sure if I'm missing some important problem with that approach and would be happy about input in that regard.

Start in src/openvpn/multi.c at multi_client_connect_post and trace where override_locked_username and OPENVPN_PLUGIN_CLIENT_CONNECT_V2 are handled. Reproduce the two-plugin setup described in the issue, then verify that the second plugin receives the updated username in its envp-array after the first applies client_config_file. No specific test file is mentioned.