This is the first beta release of version 2.3 series. Changes from version 2.2.5 are as follows.

• [core] forbid empty path string in configuration #1506 (Ichito Nagata)
• [core] use eventfd instead of pipe on linux #1533 (Baodong Chen)
• [core] remove redundancy #1568 #1569 #1584 #1596 (Baodong Chen)
• [core] !env for respecting environment variables from the configuration file #1524 (Yannick Koechlin)
• [core] avoid copying vector when calling writev #1600 (Kazuho Oku)
• [core] alignment-aware allocation from memory pool #1605 (Baodong Chen)
• [core] stash directive for storing arbitrary YAML data #1739 (Ichito Nagata)
• [access-log] log connections that closed prior to sending a response #1235 (Kazuho Oku)
• [compress] update brotli to 1.0.2 #1523 (Kazuho Oku)
• [fastcgi] accept default as a keyword of the extensions attribute #1414 (Ichito Nagata)
• [fastcgi] add verbose mode to fastcgi-cgi gateway #1466 (Kazuho Oku)
• [fastcgi][mruby][proxy] do not delay sending the headers until some chunk of body becomes available #1508 (Ichito Nagata)