[meld/meld-3-16] Fix saving of text created in blank comparison (bgo#771498)

[Kai Willadsen <kaiw src gnome org>]

commit 6ac663a2ebe6eb0dff0e6ebecb4513d407ec4db6
Author: Vasily Galkin <galkin-vv ya ru>
Date:   Sat Sep 17 12:08:33 2016 +0300

    Fix saving of text created in blank comparison (bgo#771498)

 meld/filediff.py |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/meld/filediff.py b/meld/filediff.py
index c68f48d..0bde620 100644
--- a/meld/filediff.py
+++ b/meld/filediff.py
@@ -1494,6 +1494,9 @@ class FileDiff(melddoc.MeldDoc, gnomeglade.Component):
         text = text_type(buf.get_text(start, end, False), 'utf8')
 
         source_encoding = bufdata.sourcefile.get_encoding()
+        if not source_encoding:
+            # no encoding for new blank comparison
+            source_encoding = GtkSource.Encoding.get_utf8()
         while isinstance(text, unicode):
             try:
                 encoding = source_encoding.get_charset()