Merge branch 'maint'

* maint:
  sha1_file.c: resolve confusion EACCES vs EPERM
  sha1_file: avoid bogus "file exists" error message
  git checkout: don't warn about unborn branch if -f is already passed
  bash: offer refs instead of filenames for 'git revert'
  bash: remove dashed command leftovers
  git-p4: fix keyword-expansion regex
  fast-export: use an unsorted string list for extra_refs
  Add new testcase to show fast-export does not always exports all tags

diff --cc builtin-checkout.c
Simple merge

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

diff --cc contrib/fast-import/git-p4
Simple merge

diff --cc sha1_file.c
Simple merge

diff --cc t/t9301-fast-export.sh
Simple merge