Intermediate commit on my way to get this finalized.

Renamed context manager 'with_environment' to 'custom_environment'.
On my way to implement sshkey test.

Author: Byron

doc/source/tutorial.rst

@@ -384,7 +384,7 @@ Change configuration for a specific remote only::
     
     o.config_writer.set("pushurl", "other_url")
 
-You can also specify an SSH key to use for any operations on the remotes:
+You can also specify an SSH key to use for any operations on the remotes::
 
     private_key_file = project_dir+'id_rsa_deployment_key'
     with repo.git.sshkey(private_key_file):

git/cmd.py

@@ -439,6 +439,10 @@ def _set_cache_(self, attr):
             super(Git, self)._set_cache_(attr)
         # END handle version info
 
+    def _sshkey_script_path(self):
+        this_dir = os.path.dirname(__file__)
+        return os.path.join(this_dir, 'scripts', 'ssh_wrapper.sh')
+
     @property
     def working_dir(self):
         """:return: Git directory we are working on"""
@@ -541,6 +545,7 @@ def execute(self, command,
         # Start the process
         env = os.environ.copy()
         env["LC_MESSAGES"] = "C"
+        print(self._environment)
         env.update(self._environment)
 
         proc = Popen(command,
@@ -633,7 +638,7 @@ def update_environment(self, **kwargs):
         :return: dict that maps environment variables to their old values
         """
         old_env = {}
-        for key, value in kwargs.iteritems():
+        for key, value in kwargs.items():
             # set value if it is None
             if value is not None:
                 if key in self._environment:
@@ -648,14 +653,14 @@ def update_environment(self, **kwargs):
         return old_env
 
     @contextmanager
-    def with_environment(self, **kwargs):
+    def custom_environment(self, **kwargs):
         """
-        A context manager around the above update_environment to restore the
+        A context manager around the above ``update_environment`` method to restore the
         environment back to its previous state after operation.
 
         ``Examples``::
 
-            with self.with_environment(GIT_SSH='/bin/ssh_wrapper'):
+            with self.custom_environment(GIT_SSH='/bin/ssh_wrapper'):
                 repo.remotes.origin.fetch()
 
         :param kwargs: see update_environment
@@ -667,22 +672,20 @@ def with_environment(self, **kwargs):
             self.update_environment(**old_env)
 
     @contextmanager
-    def sshkey(self, sshkey_file):
+    def sshkey(self, sshkey_file_path):
         """
         A context manager to temporarily set an SSH key for all operations that
         run inside it.
 
         ``Examples``::
 
-            with self.environment(GIT_SSH=project_dir+'deployment_key'):
+            with self.sshkey('deployment_key'):
                 repo.remotes.origin.fetch()
 
-        :param sshkey_file: Path to a private SSH key file
+        :param sshkey_file_path: Path to a private SSH key file
         """
-        this_dir = os.path.dirname(__file__)
-        ssh_wrapper = os.path.join(this_dir, '..', 'scripts', 'ssh_wrapper.py')
-
-        with self.with_environment(GIT_SSH_KEY_FILE=sshkey_file, GIT_SSH=ssh_wrapper):
+        ssh_wrapper = self._sshkey_script_path()
+        with self.custom_environment(GIT_SSH_KEY_FILE=sshkey_file_path, GIT_SSH=ssh_wrapper):
             yield
 
     def transform_kwargs(self, split_single_char_options=False, **kwargs):

git/scripts/ssh_wrapper.sh

@@ -0,0 +1,2 @@
+#!/usr/bin/env sh
+ssh -i "$GIT_SSH_KEY_FILE" $@

git/test/test_git.py

@@ -4,18 +4,24 @@
 #
 # This module is part of GitPython and is released under
 # the BSD License: http://www.opensource.org/licenses/bsd-license.php
-
 import os
 import mock
-from git.test.lib import (TestBase,
-                          patch,
-                          raises,
-                          assert_equal,
-                          assert_true,
-                          assert_match,
-                          fixture_path)
-from git import (Git,
-                 GitCommandError)
+
+from git.test.lib import (
+    TestBase,
+    patch,
+    raises,
+    assert_equal,
+    assert_true,
+    assert_match,
+    fixture_path
+)
+from git import (
+    Git,
+    GitCommandError,
+    Repo
+)
+from gitdb.test.lib import with_rw_directory
 
 from git.compat import PY3
 
@@ -154,12 +160,13 @@ def test_env_vars_passed_to_git(self):
         with mock.patch.dict('os.environ', {'GIT_EDITOR': editor}):
             assert self.git.var("GIT_EDITOR") == editor
 
-    def test_environment(self):
+    @with_rw_directory
+    def test_environment(self, rw_dir):
         # sanity check
         assert self.git.environment() == {}
 
         # make sure the context manager works and cleans up after itself
-        with self.git.with_environment(PWD='/tmp'):
+        with self.git.custom_environment(PWD='/tmp'):
             assert self.git.environment() == {'PWD': '/tmp'}
 
         assert self.git.environment() == {}
@@ -173,3 +180,12 @@ def test_environment(self):
         new_env = self.git.update_environment(**old_env)
         assert new_env == {'VARKEY': 'VARVALUE'}
         assert self.git.environment() == {}
+
+        rw_repo = Repo.init(os.path.join(rw_dir, 'repo'))
+        remote = rw_repo.create_remote('ssh-origin', "ssh://git@server/foo")
+
+        with rw_repo.git.sshkey('doesntexist.key'):
+            remote.fetch()
+        # end
+
+