relay: fix connection with IRC clients sending "CAP REQ :" (without capability) and not sending "CAP END" (issue #1040, issue #1796)

The bug was fixed in version 2.0 (issue #1040) but a regression in version 3.7
happened while using the new IRC parser for message arguments (issue #1796,
commit 96ed471261).

ChangeLog.adoc

@@ -100,6 +100,7 @@ Bug fixes::
   * irc: fix split of CTCP message with no arguments
   * irc: remove extra space in CTCP ACTION message sent without arguments
   * lua: fix crash with print when the value to print is not a string (issue #1904, issue #1905)
+  * relay: fix connection with IRC clients sending "CAP REQ :" (without capability) and not sending "CAP END" (issue #1040)
   * ruby: fix crash on quit when a child process is still running (issue #1889, issue #1915)
   * ruby: fix crash in display of exception backtrace with Ruby 3 (issue #1631, issue #1886)
   * script: remove trailing "J" (line feed char) in source of scripts displayed

src/plugins/relay/irc/relay-irc.c

@@ -1322,6 +1322,8 @@ relay_irc_recv_command_capab (struct t_relay_client *client,
         server_caps = RELAY_IRC_DATA(client, server_capabilities);
         for (i = 1; i < num_params; i++)
         {
+            if (!params[i][0])
+                continue;
             num_caps_received++;
             capability = relay_irc_search_server_capability (params[i]);
             if (capability >= 0)