Merge branch 'bw/pathspec-sans-the-index'

Simplify parse_pathspec() codepath and stop it from looking at the
default in-core index.

* bw/pathspec-sans-the-index:
  pathspec: convert find_pathspecs_matching_against_index to take an index
  pathspec: remove PATHSPEC_STRIP_SUBMODULE_SLASH_CHEAP
  ls-files: prevent prune_cache from overeagerly pruning submodules
  pathspec: remove PATHSPEC_STRIP_SUBMODULE_SLASH_EXPENSIVE flag
  submodule: add die_in_unpopulated_submodule function
  pathspec: provide a more descriptive die message

submodule.h

@@ -49,6 +49,10 @@ extern int is_submodule_initialized(const char *path);
  * Otherwise the return error code is the same as of resolve_gitdir_gently.
  */
 extern int is_submodule_populated_gently(const char *path, int *return_error_code);
+extern void die_in_unpopulated_submodule(const struct index_state *istate,
+					 const char *prefix);
+extern void die_path_inside_submodule(const struct index_state *istate,
+				      const struct pathspec *ps);
 extern int parse_submodule_update_strategy(const char *value,
 		struct submodule_update_strategy *dst);
 extern const char *submodule_strategy_to_string(const struct submodule_update_strategy *s);