fep_cmd = ['git', '-C', args.source, 'fast-export', '--show-original-ids', '--progress=128'
           , '--signed-tags=strip', '--tag-of-filtered-object=rewrite', '--mark-tags'
           , '--fake-missing-tagger', '--reference-excluded-parents', '--all']
fep = subproc.Popen(fep_cmd, bufsize=-1, stdout=subproc.PIPE)
inpt = fep.stdout
fip_cmd = ['git', '-C', args.target, '-c', 'core.ignorecase=false'
           , 'fast-import', '--force']
fip = subproc.Popen(fip_cmd, bufsize=-1, stdin=subproc.PIPE, stdout=subproc.PIPE)
otpt = fip.stdin
processor = Processor(args.source, args.secondary, otpt, fip.stdout)
parser = gfr.FastExportParser(blob_callback = processor.blob_callback
                              , commit_callback = processor.commit_callback
                              , progress_callback = processor.progress_cb)
parser.run(inpt, otpt)
otpt.close()
inpt.close()

class Commit(_GitElementWithId):
  """
  This class defines our representation of commit elements. Commit elements
  contain all the information associated with a commit.
  """
  def __init__(self, branch,
               author_name,    author_email,    author_date,
               committer_name, committer_email, committer_date,
               message,
               file_changes,
               parents,
               original_id = None,
               encoding = None, # encoding for message; None implies UTF-8
               **kwargs):
        pass
class Processor :
    def process_commit(self, commit) :
        idx = len(commit.file_changes)
        commit.message = self.message_reformat(commit.message)
        while idx > 0 :
            idx -= 1
            fc = commit.file_changes[idx]
            if fc.type == b'M' :
                process_meth = self.MAP.get(fc.filename)
                if process_meth is not None:
                    commit.file_changes.pop(idx)
                    process_meth(commit, fc)

def process_secondary_version(self, commit) :
        parent = commit.original_id.decode('ascii')
        res = subproc.run(['git', '-C', self.prepo, 'cat-file'
                           , 'blob', f'{parent}^:secondary.version']
                          , capture_output = True)
        hsh_from = res.stdout[:40].decode('ascii')
        if len(hsh_from) < 40 :
            sr_range = f'{hsh}^!'
        else :
            sr_range = f'{hsh_from}..{hsh}'
        self.sub_parsed = False
        self.super_commit = commit
        self.sub_top_hsh = hsh.encode('ascii')
        sub_fep_cmd = ['git', '-C', self.srepo, 'fast-export', '--show-original-ids'
                       , '--signed-tags=strip', '--tag-of-filtered-object=drop'
                       , '--import-marks=secondary.marks'
                       , sr_range]
        sub_fep = subproc.Popen(sub_fep_cmd, bufsize=-1, stdout=subproc.PIPE)
        self.sub_parser.run(sub_fep.stdout, self.output)
        sub_fep.stdout.close()