xml.dom.pulldom splits text data at buffer size when parsing from file

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-09-02.16:25:02.036>
labels = ['type-bug', '3.8', '3.9', '3.7', 'library', 'docs']
title = 'xml.dom.pulldom splits text data at buffer size when parsing from file'
updated_at = <Date 2019-09-02.17:39:20.172>
user = 'https://bugs.python.org/nsturmwind'

bugs.python.org fields:

activity = <Date 2019-09-02.17:39:20.172>
actor = 'scoder'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation', 'Library (Lib)']
creation = <Date 2019-09-02.16:25:02.036>
creator = 'nsturmwind'
dependencies = []
files = ['48581']
hgrepos = []
issue_num = 38011
keywords = []
message_count = 4.0
messages = ['351021', '351023', '351024', '351026']
nosy_count = 3.0
nosy_names = ['scoder', 'docs@python', 'nsturmwind']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue38011'
versions = ['Python 3.7', 'Python 3.8', 'Python 3.9']