Release 2017.9.1X forthcoming

[Hainish]

cc @jsha @pde @J0WI @diracdeltas @jeremyn @gloomy-ghost

Scheduled for Monday or Tuesday, with significant memory usage improvements (thanks @cschanaj!)

[cschanaj]

@Hainish ruleset-whitelist.csv is sorting improperly, it would be great if you can have a look at #11942 before making the next release. thanks!!

[Hainish]

Release made #12531