msgfmt should be able to merge more than one po file

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2018-11-28.07:26:19.119>
labels = ['type-feature', '3.8']
title = 'msgfmt should be able to merge more than one po file'
updated_at = <Date 2018-12-03.20:27:44.268>
user = 'https://github.com/s-ball'

bugs.python.org fields:

activity = <Date 2018-12-03.20:27:44.268>
actor = 's-ball'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Demos and Tools']
creation = <Date 2018-11-28.07:26:19.119>
creator = 's-ball'
dependencies = []
files = ['47966']
hgrepos = []
issue_num = 35335
keywords = ['patch']
message_count = 8.0
messages = ['330575', '330608', '330701', '330704', '330859', '330897', '330977', '330979']
nosy_count = 4.0
nosy_names = ['ezio.melotti', 'eric.araujo', 'SilentGhost', 's-ball']
pr_nums = ['10875']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue35335'
versions = ['Python 3.8']