[babl] babl: check both source/dest bits/component in bad_idea()

[Øyvind Kolås <ok src gnome org>]

commit f56dbf115cd31ba6e591827388bdd3f65c86b289
Author: Øyvind Kolås <pippin gimp org>
Date:   Mon Sep 25 21:00:08 2017 +0200

    babl: check both source/dest bits/component in bad_idea()

 babl/babl-fish-path.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/babl/babl-fish-path.c b/babl/babl-fish-path.c
index 6b2874b..2a71464 100644
--- a/babl/babl-fish-path.c
+++ b/babl/babl-fish-path.c
@@ -165,7 +165,8 @@ bad_idea (const Babl *from, const Babl *to, const Babl *format)
   {
     return 1;
   }
-  if (from->format.type[0]->bits > format->format.type[0]->bits)
+  if (from->format.type[0]->bits > format->format.type[0]->bits &&
+      to->format.type[0]->bits > format->format.type[0]->bits)
   {
     /* XXX: perhaps we especially avoid going to half-float, when
      * going between u16 formats as well? */