Merge branch 'sp/maint-bash-completion-optim' into maint

* sp/maint-bash-completion-optim:
  bash completion: Resolve git show ref:path<tab> losing ref: portion
  bash completion: Append space after file names have been completed
  bash completion: Don't offer "a.." as a completion for "a."
  bash completion: Improve responsiveness of git-log completion