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

Author: gitster

contrib/completion/git-completion.bash

@@ -2431,7 +2431,7 @@ if [[ -n ${ZSH_VERSION-} ]]; then
 				--*=*|*.) ;;
 				*) c="$c " ;;
 				esac
-				array+=("$c")
+				array[$#array+1]="$c"
 			done
 			compset -P '*[=:]'
 			compadd -Q -S '' -p "${2-}" -a -- array && _ret=0