{
        const char *orig = path;
        char *sanitized = xmalloc(len + strlen(path) + 1);
-       if (*orig == '/')
+       if (is_absolute_path(orig))
                strcpy(sanitized, path);
        else {
                if (len)
        }
        if (sanitary_path_copy(sanitized, sanitized))
                goto error_out;
-       if (*orig == '/') {
+       if (is_absolute_path(orig)) {
                const char *work_tree = get_git_work_tree();
                size_t len = strlen(work_tree);
                size_t total = strlen(sanitized) + 1;
                const char *p = prefix_path(prefix, prefixlen, *src);
                if (p)
                        *(dst++) = p;
+               else
+                       exit(128); /* error message already given */
                src++;
        }
        *dst = NULL;
        const char *gitdirenv;
        int len, offset;
 
+       /*
+        * Let's assume that we are in a git repository.
+        * If it turns out later that we are somewhere else, the value will be
+        * updated accordingly.
+        */
+       if (nongit_ok)
+               *nongit_ok = 0;
+
        /*
         * If GIT_DIR is set explicitly, we're not going
         * to do any discovery, but we still do repository
        } else if (strcmp(var, "core.worktree") == 0) {
                if (!value)
                        return config_error_nonbool(var);
-               if (git_work_tree_cfg)
-                       free(git_work_tree_cfg);
+               free(git_work_tree_cfg);
                git_work_tree_cfg = xstrdup(value);
                inside_work_tree = -1;
        }