Merge branch 'jc/name' into next

* jc/name:
  sha1_name: make core.warnambiguousrefs the default.
  sha1_name: warning ambiguous refs.

diff --combined blame.c
index 7e88833,270ca52..396defc
--- 1/blame.c
--- 2/blame.c
+++ b/blame.c
@@@ -748,10 -748,11 +748,11 @@@ int main(int argc, const char **argv
        struct commit_info ci;
        const char *buf;
        int max_digits;
 -      size_t longest_file, longest_author;
 +      int longest_file, longest_author;
        int found_rename;
  
        const char* prefix = setup_git_directory();
+       git_config(git_default_config);
  
        for(i = 1; i < argc; i++) {
                if(options) {

diff --combined ls-tree.c
index 97f09bd,58663ff..26258c3
--- 1/ls-tree.c
--- 2/ls-tree.c
+++ b/ls-tree.c
@@@ -13,14 -13,13 +13,14 @@@ static int line_termination = '\n'
  #define LS_TREE_ONLY 2
  #define LS_SHOW_TREES 4
  #define LS_NAME_ONLY 8
 +static int abbrev = 0;
  static int ls_options = 0;
  const char **pathspec;
  static int chomp_prefix = 0;
  static const char *prefix;
  
  static const char ls_tree_usage[] =
 -      "git-ls-tree [-d] [-r] [-t] [-z] [--name-only] [--name-status] [--full-name] <tree-ish> [path...]";
 +      "git-ls-tree [-d] [-r] [-t] [-z] [--name-only] [--name-status] [--full-name] [--abbrev[=<n>]] <tree-ish> [path...]";
  
  static int show_recursive(const char *base, int baselen, const char *pathname)
  {
@@@ -74,9 -73,7 +74,9 @@@ static int show_tree(unsigned char *sha
                return 0;
  
        if (!(ls_options & LS_NAME_ONLY))
 -              printf("%06o %s %s\t", mode, type, sha1_to_hex(sha1));
 +              printf("%06o %s %s\t", mode, type,
 +                              abbrev ? find_unique_abbrev(sha1,abbrev)
 +                                      : sha1_to_hex(sha1));
        write_name_quoted(base + chomp_prefix, baselen - chomp_prefix,
                          pathname,
                          line_termination, stdout);
@@@ -90,6 -87,7 +90,7 @@@ int main(int argc, const char **argv
        struct tree *tree;
  
        prefix = setup_git_directory();
+       git_config(git_default_config);
        if (prefix && *prefix)
                chomp_prefix = strlen(prefix);
        while (1 < argc && argv[1][0] == '-') {
@@@ -116,18 -114,6 +117,18 @@@
                                chomp_prefix = 0;
                                break;
                        }
 +                      if (!strncmp(argv[1]+2, "abbrev=",7)) {
 +                              abbrev = strtoul(argv[1]+9, NULL, 10);
 +                              if (abbrev && abbrev < MINIMUM_ABBREV)
 +                                      abbrev = MINIMUM_ABBREV;
 +                              else if (abbrev > 40)
 +                                      abbrev = 40;
 +                              break;
 +                      }
 +                      if (!strcmp(argv[1]+2, "abbrev")) {
 +                              abbrev = DEFAULT_ABBREV;
 +                              break;
 +                      }
                        /* otherwise fallthru */
                default:
                        usage(ls_tree_usage);