Merge branch 'hv/submodule-alt-odb' into maint

When a submodule repository uses alternate object store mechanism, some
commands that were started from the superproject did not notice it and
failed with "No such object" errors.  The subcommands of "git submodule"
command that recursed into the submodule in a separate process were OK;
only the ones that cheated and peeked directly into the submodule's
repository from the primary process were affected.

By Heiko Voigt
* hv/submodule-alt-odb:
teach add_submodule_odb() to look for alternates

diff --combined cache.h
index 5bf59ff5c33919ac42ee79dea7911a773c1f698d,3a28cb13b3790e1752615ec1aa4be948edfd4390..84b82297484df95c6908c5d4571d63f9f04e601f
--- 1/cache.h
--- 2/cache.h
+++ b/cache.h
@@@ -625,8 -625,7 +625,8 @@@ enum push_default_type 
        PUSH_DEFAULT_NOTHING = 0,
        PUSH_DEFAULT_MATCHING,
        PUSH_DEFAULT_UPSTREAM,
 -      PUSH_DEFAULT_CURRENT
 +      PUSH_DEFAULT_CURRENT,
 +      PUSH_DEFAULT_UNSPECIFIED
  };
  
  extern enum branch_track git_branch_track;
@@@ -709,19 -708,6 +709,19 @@@ static inline void hashclr(unsigned cha
  #define EMPTY_TREE_SHA1_BIN \
         ((const unsigned char *) EMPTY_TREE_SHA1_BIN_LITERAL)
  
 +#define EMPTY_BLOB_SHA1_HEX \
 +      "e69de29bb2d1d6434b8b29ae775ad8c2e48c5391"
 +#define EMPTY_BLOB_SHA1_BIN_LITERAL \
 +      "\xe6\x9d\xe2\x9b\xb2\xd1\xd6\x43\x4b\x8b" \
 +      "\x29\xae\x77\x5a\xd8\xc2\xe4\x8c\x53\x91"
 +#define EMPTY_BLOB_SHA1_BIN \
 +      ((const unsigned char *) EMPTY_BLOB_SHA1_BIN_LITERAL)
 +
 +static inline int is_empty_blob_sha1(const unsigned char *sha1)
 +{
 +      return !hashcmp(sha1, EMPTY_BLOB_SHA1_BIN);
 +}
 +
  int git_mkstemp(char *path, size_t n, const char *template);
  
  int git_mkstemps(char *path, size_t n, const char *template, int suffix_len);
@@@ -942,22 -928,6 +942,22 @@@ extern const char *fmt_name(const char 
  extern const char *git_editor(void);
  extern const char *git_pager(int stdout_is_tty);
  
 +struct ident_split {
 +      const char *name_begin;
 +      const char *name_end;
 +      const char *mail_begin;
 +      const char *mail_end;
 +      const char *date_begin;
 +      const char *date_end;
 +      const char *tz_begin;
 +      const char *tz_end;
 +};
 +/*
 + * Signals an success with 0, but time part of the result may be NULL
 + * if the input lacks timestamp and zone
 + */
 +extern int split_ident_line(struct ident_split *, const char *, int);
 +
  struct checkout {
        const char *base_dir;
        int base_dir_len;
@@@ -980,9 -950,7 +980,9 @@@ struct cache_def 
  extern int has_symlink_leading_path(const char *name, int len);
  extern int threaded_has_symlink_leading_path(struct cache_def *, const char *, int);
  extern int check_leading_path(const char *name, int len);
 +extern int threaded_check_leading_path(struct cache_def *cache, const char *name, int len);
  extern int has_dirs_only_path(const char *name, int len, int prefix_len);
 +extern int threaded_has_dirs_only_path(struct cache_def *cache, const char *name, int len, int prefix_len);
  extern void schedule_dir_for_removal(const char *name, int len);
  extern void remove_scheduled_dirs(void);
  
@@@ -992,6 -960,7 +992,7 @@@ extern struct alternate_object_databas
        char base[FLEX_ARRAY]; /* more */
  } *alt_odb_list;
  extern void prepare_alt_odb(void);
+ extern void read_info_alternates(const char * relative_base, int depth);
  extern void add_to_alternates_file(const char *reference);
  typedef int alt_odb_fn(struct alternate_object_database *, void *);
  extern void foreach_alt_odb(alt_odb_fn, void*);
@@@ -1147,8 -1116,6 +1148,8 @@@ extern int git_config_from_file(config_
  extern void git_config_push_parameter(const char *text);
  extern int git_config_from_parameters(config_fn_t fn, void *data);
  extern int git_config(config_fn_t fn, void *);
 +extern int git_config_with_options(config_fn_t fn, void *,
 +                                 const char *filename, int respect_includes);
  extern int git_config_early(config_fn_t fn, void *, const char *repo_config);
  extern int git_parse_ulong(const char *, unsigned long *);
  extern int git_config_int(const char *, const char *);
@@@ -1164,7 -1131,6 +1165,7 @@@ extern int git_config_parse_key(const c
  extern int git_config_set_multivar(const char *, const char *, const char *, int);
  extern int git_config_set_multivar_in_file(const char *, const char *, const char *, const char *, int);
  extern int git_config_rename_section(const char *, const char *);
 +extern int git_config_rename_section_in_file(const char *, const char *, const char *);
  extern const char *git_etc_gitconfig(void);
  extern int check_repository_format_version(const char *var, const char *value, void *cb);
  extern int git_env_bool(const char *, int);
@@@ -1175,13 -1141,7 +1176,13 @@@ extern const char *get_commit_output_en
  
  extern int git_config_parse_parameter(const char *, config_fn_t fn, void *data);
  
 -extern const char *config_exclusive_filename;
 +struct config_include_data {
 +      int depth;
 +      config_fn_t fn;
 +      void *data;
 +};
 +#define CONFIG_INCLUDE_INIT { 0 }
 +extern int git_config_include(const char *name, const char *value, void *data);
  
  #define MAX_GITNAME (1000)
  extern char git_default_email[MAX_GITNAME];
@@@ -1219,7 -1179,6 +1220,7 @@@ extern const char *pager_program
  extern int pager_in_use(void);
  extern int pager_use_color;
  extern int term_columns(void);
 +extern int decimal_width(int);
  
  extern const char *editor_program;
  extern const char *askpass_program;
@@@ -1306,6 -1265,4 +1307,6 @@@ extern struct startup_info *startup_inf
  /* builtin/merge.c */
  int checkout_fast_forward(const unsigned char *from, const unsigned char *to);
  
 +int sane_execvp(const char *file, char *const argv[]);
 +
  #endif /* CACHE_H */