Merge branch 'bc/fix-array-syntax-for-3.0-in-completion-bash' into maint

Command line completion code was inadvertently made incompatible with
older versions of bash by using a newer array notation.

* bc/fix-array-syntax-for-3.0-in-completion-bash:
  git-completion.bash: replace zsh notation that breaks bash 3.X

diff --cc contrib/completion/git-completion.bash
Simple merge