[meld] ui.cellrenderers: Make getter defaults consistent with our empty state

[Kai Willadsen <kaiw src gnome org>]

commit 37451c02c3f2e3ebb8baf9843246d020591042d0
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Sep 2 10:28:00 2018 +1000

    ui.cellrenderers: Make getter defaults consistent with our empty state
    
    Defaulting these getters to None isn't really what we want, because we
    actually consider -1 to be our "empty" state now that we're not using
    pygobjects for the columns.

 meld/ui/cellrenderers.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/meld/ui/cellrenderers.py b/meld/ui/cellrenderers.py
index 807e5bb3..11a85d9e 100644
--- a/meld/ui/cellrenderers.py
+++ b/meld/ui/cellrenderers.py
@@ -26,7 +26,7 @@ class CellRendererDate(Gtk.CellRendererText):
     DATETIME_FORMAT = "%a %d %b %Y %H:%M:%S"
 
     def get_timestamp(self):
-        return getattr(self, '_datetime', None)
+        return getattr(self, '_datetime', -1.0)
 
     def set_timestamp(self, value):
         if value == self.get_timestamp():
@@ -52,7 +52,7 @@ class CellRendererByteSize(Gtk.CellRendererText):
     __gtype_name__ = "CellRendererByteSize"
 
     def get_bytesize(self):
-        return getattr(self, '_bytesize', None)
+        return getattr(self, '_bytesize', -1)
 
     def set_bytesize(self, value):
         if value == self.get_bytesize():
@@ -86,7 +86,7 @@ class CellRendererFileMode(Gtk.CellRendererText):
     __gtype_name__ = "CellRendererFileMode"
 
     def get_file_mode(self):
-        return getattr(self, '_file_mode', None)
+        return getattr(self, '_file_mode', -1)
 
     def set_file_mode(self, value):
         if value == self.get_file_mode():