Nginx 0.7.42 增加了一些配置项，以及修复了bug。
*) Change: now the "Invalid argument" error returned by setsockopt(TCP_NODELAY) on Solaris, is ignored.
*) Change: now if a file specified in a "auth_basic_user_file" directive is absent, then the 405 error is returned instead of the 500 one.
*) Feature: the "auth_basic_user_file" directive supports variables.
*) Feature: the "listen" directive supports the "ipv6only" parameter.
*) Bugfix: in an "alias" directive with references to captures of regular expressions; the bug had appeared in 0.7.40.
*) Bugfix: compatibility with Tru64 UNIX.
*) Bugfix: nginx could not be built without PCRE library; the bug had appeared in 0.7.41.