fix(repo): make it serializable with pickle

It's entirely untested if this repo still does the right thing,
but I'd think it does.

Fixes #504

Author: Byron

doc/source/changes.rst

@@ -6,6 +6,7 @@ Changelog
 =============================
 
 * `tag.commit` will now resolve commits deeply.
+* `Repo` objects can now be pickled, which helps with multi-processing.
 
 * `DiffIndex.iter_change_type(...)` produces better results when diffing
 2.0.8 - Features and Bugfixes

git/cmd.py

@@ -213,6 +213,17 @@ def _deplete_buffer(fno, handler, buf_list, wg=None):
 
 def dashify(string):
     return string.replace('_', '-')
+    
+
+def slots_to_dict(self, exclude=()):
+    return dict((s, getattr(self, s)) for s in self.__slots__ if s not in exclude)
+    
+
+def dict_to_slots_and__excluded_are_none(self, d, excluded=()):
+    for k, v in d.items():
+        setattr(self, k, v)
+    for k in excluded:
+        setattr(self, k, None)
 
 ## -- End Utilities -- @}
 
@@ -235,7 +246,15 @@ class Git(LazyMixin):
     """
     __slots__ = ("_working_dir", "cat_file_all", "cat_file_header", "_version_info",
                  "_git_options", "_environment")
-
+                 
+    _excluded_ = ('cat_file_all', 'cat_file_header', '_version_info')
+    
+    def __getstate__(self):
+        return slots_to_dict(self, exclude=self._excluded_)
+        
+    def __setstate__(self, d):
+        dict_to_slots_and__excluded_are_none(self, d, excluded=self._excluded_)
+        
     # CONFIGURATION
     # The size in bytes read from stdout when copying git's output to another stream
     max_chunk_size = 1024 * 64

git/repo/base.py

@@ -93,7 +93,6 @@ class Repo(object):
 
     'git_dir' is the .git repository directory, which is always set."""
     DAEMON_EXPORT_FILE = 'git-daemon-export-ok'
-    __slots__ = ("working_dir", "_working_tree_dir", "git_dir", "_bare", "git", "odb")
 
     # precompiled regex
     re_whitespace = re.compile(r'\s+')

git/test/test_repo.py

@@ -4,6 +4,8 @@
 #
 # This module is part of GitPython and is released under
 # the BSD License: http://www.opensource.org/licenses/bsd-license.php
+import pickle
+
 from git.test.lib import (
     patch,
     TestBase,
@@ -104,13 +106,15 @@ def test_tree_from_revision(self):
 
         # try from invalid revision that does not exist
         self.failUnlessRaises(BadName, self.rorepo.tree, 'hello world')
+        
+    def test_pickleable(self):
+        pickle.loads(pickle.dumps(self.rorepo))
 
     def test_commit_from_revision(self):
         commit = self.rorepo.commit('0.1.4')
         assert commit.type == 'commit'
         assert self.rorepo.commit(commit) == commit
 
-    def test_commits(self):
         mc = 10
         commits = list(self.rorepo.iter_commits('0.1.6', max_count=mc))
         assert len(commits) == mc