Tests: use (?P<name>...) to be compatible with old PCRE versions. Perl-style syntax (?<name>...) is only supported by PCRE 7.0+, while some OSes out there still use PCRE 6.6. Since there are no problems in nginx with (?P<name>...) syntax now, it should be safe to use Python syntax instead (at worst a bit more tests will be broken in case of regression).