fix r3981 again for case "Accept-Encoding: gzip"
diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index d2b90f1..f7ebacb 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -2209,7 +2209,7 @@
             return NGX_DECLINED;
         }
 
-        if (p > start && (*(p - 1) == ',' || *(p - 1) == ' ')) {
+        if (p == start || (*(p - 1) == ',' || *(p - 1) == ' ')) {
             break;
         }