Sync with 2.18.5

* maint-2.18:
  Git 2.18.5
  Git 2.17.6
  unpack_trees(): start with a fresh lstat cache
  run-command: invalidate lstat cache after a command finished
  checkout: fix bug that makes checkout follow symlinks in leading path

diff --cc cache.h
Simple merge

diff --cc compat/mingw.c
Simple merge

diff --cc git-compat-util.h
Simple merge

diff --cc run-command.c
Simple merge

diff --cc t/t0021-conversion.sh
Simple merge

diff --cc unpack-trees.c
index 705054a66950d2a42fe9c8f33f71c3e5d90910b9,8c246a1db3887a750e919feedfb3b499bed4740f..7e023daca3cf4c7d5683311502786a06e4d5e83a
--- 1/unpack-trees.c
--- 2/unpack-trees.c
+++ b/unpack-trees.c
@@@ -352,8 -360,11 +352,11 @@@ static int check_updates(struct unpack_
  
        progress = get_progress(o);
  
+       /* Start with clean cache to avoid using any possibly outdated info. */
+       invalidate_lstat_cache();
+ 
        if (o->update)
 -              git_attr_set_direction(GIT_ATTR_CHECKOUT, index);
 +              git_attr_set_direction(GIT_ATTR_CHECKOUT);
  
        if (should_update_submodules() && o->update && !o->dry_run)
                load_gitmodules_file(index, NULL);