Merge branch 'nd/conditional-config-in-early-config'

Merge branch 'nd/conditional-config-in-early-config'

The recently introduced conditional inclusion of configuration did
not work well when early-config mechanism was involved.

* nd/conditional-config-in-early-config:
  config: correct file reading order in read_early_config()
  config: handle conditional include when $GIT_DIR is not set up
  config: prepare to pass more info in git_config_with_options()