Merge branch 'fix'

* fix:
  repack: honor -d even when no new pack was created
  clone: keep --reference even with -l -s
  repo-config: document what value_regexp does a bit more clearly.
  Release config lock if the regex is invalid
  core-tutorial.txt: escape asterisk

diff --cc Documentation/git-repo-config.txt
Simple merge

diff --cc config.c
Simple merge

diff --cc git-repack.sh
Simple merge