Log Message:
Update to 1.18.8. From the changelog:

* Work around git commit's lack of robustness, by providing reasonable
  default values for GIT_COMMITTER_EMAIL etc. This was already done as
  part of the su/sudo handling, and is now always done.
* Don't hardcode the master branch when pushing to PUSH_REMOTE.
  Instead, let git push whatever branches it is configured to push to
  that remote.
* Added some unit tests.
  Thanks, Henrik Riomar.
* etckeeper will work on systems that do not have perl installed.
  (perl is still used when available as it's faster)
  Thanks, William Johansson and radhus.
* Prevent LC_ALL overriding the LC_COLLATE used to sort metadata.
* Only show errors (no progress indicators) when pushing Git/Mercurial repos
  to avoid unncessary cron mails.
  Thanks, Nils Steinger.
* Fix regex in 20-warn-problem-files.
* Added support for apk (alpine linux)
  Thanks, Henrik Riomar.