[gobject-introspection] giscanner/transformer.py: Fix --identifier-filter on Python 3.x

[Chun-wei Fan <fanchunwei src gnome org>]

commit cb1fabbd3641cfebf7d493d6eca73eab3d2027a2
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Wed Oct 28 16:28:43 2015 +0800

    giscanner/transformer.py: Fix --identifier-filter on Python 3.x
    
    We need to encode the identifier-filter command to bytes, and decode its
    outputs to ascii in order for it to work on Python 3.x.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=757126

 giscanner/transformer.py |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/giscanner/transformer.py b/giscanner/transformer.py
index 3183d62..e8b1e04 100644
--- a/giscanner/transformer.py
+++ b/giscanner/transformer.py
@@ -326,10 +326,11 @@ raise ValueError."""
                                     stdout=subprocess.PIPE,
                                     stderr=subprocess.PIPE,
                                     shell=True)
-            ident, err = proc.communicate(ident)
+            proc_ident, err = proc.communicate(ident.encode())
             if proc.returncode:
                 raise ValueError('filter: "%s" exited: %d with error: %s' %
                                  (self._identifier_filter_cmd, proc.returncode, err))
+            ident = proc_ident.decode('ascii')
 
         hidden = ident.startswith('_')
         if hidden: