use buffer_string_set_length() to truncate strings

src/configparser.y

@@ -495,7 +495,7 @@ context ::= DOLLAR SRVVARNAME(B) LBRACKET stringop(C) RBRACKET cond(E) expressio
           }
           else {
             int rc;
-            buffer_commit(rvalue, (size_t)(slash - rvalue->ptr)); /*(truncate)*/
+            buffer_string_set_length(rvalue, (size_t)(slash - rvalue->ptr)); /*(truncate)*/
             rc = http_request_host_normalize(rvalue);
             buffer_append_string_len(rvalue, CONST_STR_LEN("/"));
             buffer_append_int(rvalue, (int)nm_bits);

src/request.c

@@ -302,7 +302,7 @@ int http_request_host_normalize(buffer *b) {
         if (1 != rc) return -1;
 
         inet_ntop(AF_INET6,(const void *)&addr, buf, sizeof(buf));
-        buffer_commit(b, 1); /* truncate after '[' */
+        buffer_string_set_length(b, 1); /* truncate after '[' */
         buffer_append_string(b, buf);
         buffer_append_string_len(b, CONST_STR_LEN("]"));