[meld/VersionControlRework: 22/123] meld.vc: Make _tree_cache always be a dict

[Kai Willadsen <kaiw src gnome org>]

commit e466a2bd25e6f14d76a26fda6e79a63445f9e545
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Mar 22 08:03:09 2015 +1000

    meld.vc: Make _tree_cache always be a dict

 meld/vc/_vc.py |    3 +--
 meld/vc/bzr.py |    1 -
 meld/vc/git.py |    1 -
 3 files changed, 1 insertions(+), 4 deletions(-)
---
diff --git a/meld/vc/_vc.py b/meld/vc/_vc.py
index 599a3f0..c8b87b6 100644
--- a/meld/vc/_vc.py
+++ b/meld/vc/_vc.py
@@ -121,7 +121,7 @@ class Vc(object):
         self.root, self.location = self.is_in_repo(path)
         if not self.root:
             raise ValueError
-        self._tree_cache = None
+        self._tree_cache = {}
 
     def commit_command(self, message):
         raise NotImplementedError()
@@ -194,7 +194,6 @@ class Vc(object):
 
     def _get_tree_cache(self):
         if not self._tree_cache:
-            self._tree_cache = {}
             self._update_tree_state_cache("./", self._tree_cache)
         return self._tree_cache
 
diff --git a/meld/vc/bzr.py b/meld/vc/bzr.py
index dedf1f0..22b0936 100644
--- a/meld/vc/bzr.py
+++ b/meld/vc/bzr.py
@@ -92,7 +92,6 @@ class Vc(_vc.Vc):
 
     def __init__(self, location):
         super(Vc, self).__init__(location)
-        self._tree_cache = {}
         self._tree_meta_cache = {}
 
     def commit_command(self, message):
diff --git a/meld/vc/git.py b/meld/vc/git.py
index e7ca00e..b429e41 100644
--- a/meld/vc/git.py
+++ b/meld/vc/git.py
@@ -70,7 +70,6 @@ class Vc(_vc.Vc):
 
     def __init__(self, location):
         super(Vc, self).__init__(location)
-        self._tree_cache = {}
         self._tree_meta_cache = {}
 
     @classmethod