Strange XPath search behavior of xml.etree.ElementTree.Element.find

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-01-11.17:12:45.685>
labels = ['3.8', 'type-bug', 'library']
title = 'Strange XPath search behavior of xml.etree.ElementTree.Element.find'
updated_at = <Date 2021-01-15.01:53:49.825>
user = 'https://bugs.python.org/robpats'

bugs.python.org fields:

activity = <Date 2021-01-15.01:53:49.825>
actor = 'robpats'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-01-11.17:12:45.685>
creator = 'robpats'
dependencies = []
files = []
hgrepos = []
issue_num = 42893
keywords = []
message_count = 3.0
messages = ['384851', '385011', '385094']
nosy_count = 3.0
nosy_names = ['scoder', 'christian.heimes', 'robpats']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue42893'
versions = ['Python 3.8']