always run regex in server_name to get captures for IPv6 addresses,
the same fix for IPv4 addresses has been made in r2584

src/http/ngx_http.c

diff --git a/src/http/ngx_http.c b/src/http/ngx_http.c
index 9ca52b9..5ca9fed 100644
--- a/src/http/ngx_http.c
+++ b/src/http/ngx_http.c
@@ -1871,7 +1871,11 @@
             && (addr[i].wc_head == NULL
                 || addr[i].wc_head->hash.buckets == NULL)
             && (addr[i].wc_tail == NULL
-                || addr[i].wc_tail->hash.buckets == NULL))
+                || addr[i].wc_tail->hash.buckets == NULL)
+#if (NGX_PCRE)
+            && addr[i].nregex == 0
+#endif
+            )
         {
             continue;
         }