chore(remote): added debug helper

Write debug files for stderr output as well as FETCH_INFO into
the git repository, e.g. into `.git/`

Help with #301

Author: Byron

git/remote.py

@@ -346,7 +346,7 @@ class Remote(LazyMixin, Iterable):
     NOTE: When querying configuration, the configuration accessor will be cached
     to speed up subsequent accesses."""
 
-    __slots__ = ("repo", "name", "_config_reader")
+    __slots__ = ("repo", "name", "_config_reader", "fetch_no")
     _id_attribute_ = "name"
 
     def __init__(self, repo, name):
@@ -356,6 +356,7 @@ def __init__(self, repo, name):
         :param name: the name of the remote, i.e. 'origin'"""
         self.repo = repo
         self.name = name
+        self.fetch_no = 0
 
         if os.name == 'nt':
             # some oddity: on windows, python 2.5, it for some reason does not realize
@@ -551,6 +552,9 @@ def _get_fetch_info_from_stderr(self, proc, progress):
         progress_handler = progress.new_message_handler()
 
         def my_progress_handler(line):
+            stderr_fetch = open(join(self.repo.git_dir, '%03i_debug_git-python_stderr' % self.fetch_no), 'ab')
+            stderr_fetch.write((line + '\n').encode(defenc))
+            stderr_fetch.close()
             for pline in progress_handler(line):
                 if line.startswith('fatal:') or line.startswith('error:'):
                     raise GitCommandError(("Error when fetching: %s" % line,), 2)
@@ -567,6 +571,11 @@ def my_progress_handler(line):
         # We are only interested in stderr here ...
         handle_process_output(proc, None, my_progress_handler, finalize_process)
 
+        import shutil
+        shutil.copyfile(join(self.repo.git_dir, 'FETCH_HEAD'), join(self.repo.git_dir,
+                        '%03i_debug_git-python_FETCH_HEAD' % self.fetch_no))
+        self.fetch_no += 1
+
         # read head information
         fp = open(join(self.repo.git_dir, 'FETCH_HEAD'), 'rb')
         fetch_head_info = [l.decode(defenc) for l in fp.readlines()]