hostname: properly deal with unset hostname in fedora configuration

fixme

@@ -38,6 +38,7 @@
 * place /etc/inittab with explaining blurb.
 
 * In command lines, support both "$FOO" and $FOO
+
 * /etc must always take precedence even if we follow symlinks!
 
 * vielleicht implizit immer auf syslog dependen?
@@ -48,8 +49,6 @@
 
 * set_put(), hashmap_put() return values checken. i.e. == 0 macht kein free()!
 
-* crash on missing hostname
-
 * fix merging in .swap units
 
 * pahole

src/hostname-setup.c

@@ -101,10 +101,11 @@ static int read_hostname(char **hn) {
                 }
 
                 *hn = k;
-                break;
+                r = 0;
+                goto finish;
         }
 
-        r = 0;
+        r = -ENOENT;
 
 finish:
         fclose(f);