Merge branch 'vd/loose-ref-iteration-optimization'

The code to iterate over loose references have been optimized to
reduce the number of lstat() system calls.

* vd/loose-ref-iteration-optimization:
  files-backend.c: avoid stat in 'loose_fill_ref_dir'
  dir.[ch]: add 'follow_symlink' arg to 'get_dtype'
  dir.[ch]: expose 'get_dtype'
  ref-cache.c: fix prefix matching in ref iteration

diff --cc t/t4205-log-pretty-formats.sh
Simple merge