Merge branch 'gb/maint-submodule-env' into maint

* gb/maint-submodule-env:
  is_submodule_modified(): clear environment properly
  submodules: ensure clean environment when operating in a submodule
  shell setup: clear_local_git_env() function
  rev-parse: --local-env-vars option
  Refactor list of of repo-local env vars

cache.h

@@ -388,6 +388,15 @@ static inline enum object_type object_type(unsigned int mode)
 #define GIT_NOTES_REF_ENVIRONMENT "GIT_NOTES_REF"
 #define GIT_NOTES_DEFAULT_REF "refs/notes/commits"
 
+/*
+ * Repository-local GIT_* environment variables
+ * The array is NULL-terminated to simplify its usage in contexts such
+ * environment creation or simple walk of the list.
+ * The number of non-NULL entries is available as a macro.
+ */
+#define LOCAL_REPO_ENV_SIZE 8
+extern const char *const local_repo_env[LOCAL_REPO_ENV_SIZE + 1];
+
 extern int is_bare_repository_cfg;
 extern int is_bare_repository(void);
 extern int is_inside_git_dir(void);