Merge branch 'js/maint-1.6.0-exec-path-env' into maint

* js/maint-1.6.0-exec-path-env:
  Propagate --exec-path setting to external commands via GIT_EXEC_PATH

diff --combined exec_cmd.c
index 217c12577f52b8ff9d535a086ec75d54107ee01c,589059f026bcecae99469c4514efdcfa9542e28b..408e4e55e1c58931444c772d35d23b505bf3e2ea
--- 1/exec_cmd.c
--- 2/exec_cmd.c
+++ b/exec_cmd.c
@@@ -9,58 -9,26 +9,62 @@@ static const char *argv0_path
  
  const char *system_path(const char *path)
  {
 -      if (!is_absolute_path(path) && argv0_path) {
 -              struct strbuf d = STRBUF_INIT;
 -              strbuf_addf(&d, "%s/%s", argv0_path, path);
 -              path = strbuf_detach(&d, NULL);
 +#ifdef RUNTIME_PREFIX
 +      static const char *prefix;
 +#else
 +      static const char *prefix = PREFIX;
 +#endif
 +      struct strbuf d = STRBUF_INIT;
 +
 +      if (is_absolute_path(path))
 +              return path;
 +
 +#ifdef RUNTIME_PREFIX
 +      assert(argv0_path);
 +      assert(is_absolute_path(argv0_path));
 +
 +      if (!prefix &&
 +          !(prefix = strip_path_suffix(argv0_path, GIT_EXEC_PATH)) &&
 +          !(prefix = strip_path_suffix(argv0_path, BINDIR)) &&
 +          !(prefix = strip_path_suffix(argv0_path, "git"))) {
 +              prefix = PREFIX;
 +              fprintf(stderr, "RUNTIME_PREFIX requested, "
 +                              "but prefix computation failed.  "
 +                              "Using static fallback '%s'.\n", prefix);
        }
 +#endif
 +
 +      strbuf_addf(&d, "%s/%s", prefix, path);
 +      path = strbuf_detach(&d, NULL);
        return path;
  }
  
 -void git_set_argv0_path(const char *path)
 +const char *git_extract_argv0_path(const char *argv0)
  {
 -      argv0_path = path;
 +      const char *slash;
 +
 +      if (!argv0 || !*argv0)
 +              return NULL;
 +      slash = argv0 + strlen(argv0);
 +
 +      while (argv0 <= slash && !is_dir_sep(*slash))
 +              slash--;
 +
 +      if (slash >= argv0) {
 +              argv0_path = xstrndup(argv0, slash - argv0);
 +              return slash + 1;
 +      }
 +
 +      return argv0;
  }
  
  void git_set_argv_exec_path(const char *exec_path)
  {
        argv_exec_path = exec_path;
+       /*
+        * Propagate this setting to external programs.
+        */
+       setenv(EXEC_PATH_ENVIRONMENT, exec_path, 1);
  }
  
  
@@@ -95,9 -63,13 +99,9 @@@ static void add_path(struct strbuf *out
  void setup_path(void)
  {
        const char *old_path = getenv("PATH");
 -      struct strbuf new_path;
 -
 -      strbuf_init(&new_path, 0);
 +      struct strbuf new_path = STRBUF_INIT;
  
 -      add_path(&new_path, argv_exec_path);
 -      add_path(&new_path, getenv(EXEC_PATH_ENVIRONMENT));
 -      add_path(&new_path, system_path(GIT_EXEC_PATH));
 +      add_path(&new_path, git_exec_path());
        add_path(&new_path, argv0_path);
  
        if (old_path)