[config] don't save config on set

Fixes beat.editor#277
4 jobs for config-set-dont-save in 4 minutes and 5 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #204710
docker-build
build_linux_36

00:03:04

58.0%
passed #204711
docker-build
build_linux_37

00:02:57

58.0%
passed #204708
macosx
build_macosx_36

00:04:05

58.0%
passed #204709
macosx
build_macosx_37

00:03:54

58.0%