os.sendfile() on BSD, macOS don't return bytes sent on EINTR

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-03-30.16:47:38.407>
labels = ['3.7', '3.8', 'type-bug', 'library']
title = "os.sendfile() on BSD, macOS don't return bytes sent on EINTR"
updated_at = <Date 2019-04-12.16:11:35.311>
user = 'https://github.com/giampaolo'

bugs.python.org fields:

activity = <Date 2019-04-12.16:11:35.311>
actor = 'giampaolo.rodola'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2019-03-30.16:47:38.407>
creator = 'giampaolo.rodola'
dependencies = []
files = []
hgrepos = []
issue_num = 36488
keywords = ['patch']
message_count = 4.0
messages = ['339214', '339292', '339511', '339578']
nosy_count = 3.0
nosy_names = ['giampaolo.rodola', 'rosslagerwall', 'josh.r']
pr_nums = ['12807']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue36488'
versions = ['Python 3.7', 'Python 3.8']