[gegl] buffer: rectify format==NULL earlier in gegl_buffer_get

[Øyvind Kolås <ok src gnome org>]

commit 12056e75125dcc975f47b4c0b162aa15e9ce2f08
Author: Øyvind Kolås <pippin gimp org>
Date:   Sat Jan 13 16:56:00 2018 +0100

    buffer: rectify format==NULL earlier in gegl_buffer_get

 gegl/buffer/gegl-buffer-access.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer-access.c b/gegl/buffer/gegl-buffer-access.c
index 527912f..4b5392a 100644
--- a/gegl/buffer/gegl-buffer-access.c
+++ b/gegl/buffer/gegl-buffer-access.c
@@ -1890,6 +1890,7 @@ _gegl_buffer_get_unlocked (GeglBuffer          *buffer,
       gegl_buffer_cl_cache_flush (buffer, rect);
     }
 
+
   if (scale == 1.0 &&
       rect &&
       rect->width == 1)
@@ -1902,6 +1903,9 @@ _gegl_buffer_get_unlocked (GeglBuffer          *buffer,
       }
     else
       {
+        if (format == NULL)
+          format = buffer->soft_format;
+
         gint bpp = babl_format_get_bytes_per_pixel (buffer->soft_format);
         if (!format || buffer->soft_format == format || rowstride != bpp)
         {
@@ -1922,11 +1926,11 @@ _gegl_buffer_get_unlocked (GeglBuffer          *buffer,
       }
   }
 
+  g_return_if_fail (scale > 0.0);
+
   if (format == NULL)
     format = buffer->soft_format;
 
-  g_return_if_fail (scale > 0.0);
-
   if (!rect && GEGL_FLOAT_EQUAL (scale, 1.0))
     {
       gegl_buffer_iterate_read_dispatch (buffer, &buffer->extent, dest_buf,