C implementation of parts of copy.deepcopy

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2016-11-03.23:11:36.119>
labels = ['extension-modules', '3.7', 'performance']
title = 'C implementation of parts of copy.deepcopy'
updated_at = <Date 2019-01-20.21:43:41.055>
user = 'https://github.com/villemoes'

bugs.python.org fields:

activity = <Date 2019-01-20.21:43:41.055>
actor = 'pablogsal'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Extension Modules']
creation = <Date 2016-11-03.23:11:36.119>
creator = 'villemoes'
dependencies = []
files = ['45344', '45400']
hgrepos = []
issue_num = 28607
keywords = ['patch']
message_count = 3.0
messages = ['280032', '280360', '334105']
nosy_count = 2.0
nosy_names = ['villemoes', 'pablogsal']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'test needed'
status = 'open'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue28607'
versions = ['Python 3.7']