ZoneInfo gives a surprising exception for ''

[asottile-sentry]

Bug report

Bug description:

import zoneinfo
zoneinfo.ZoneInfo('')

results in the following exception:

>>> zoneinfo.ZoneInfo('')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/asottile/.pyenv/versions/3.11.6/lib/python3.11/zoneinfo/_tzpath.py", line 67, in find_tzfile
    _validate_tzfile_path(key)
  File "/Users/asottile/.pyenv/versions/3.11.6/lib/python3.11/zoneinfo/_tzpath.py", line 91, in _validate_tzfile_path
    raise ValueError(
ValueError: ZoneInfo keys must be normalized relative paths, got: 

I expect zoneinfo.ZoneInfoNotFound instead, or some other error that's more specific about this case

it seems this stems from the code internally using the length of the normpath'd result of this string and:

>>> normpath('')
'.'

a small improvement would be to use !r in the error message as well

CPython versions tested on:

3.11, CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-114713: handle case of an empty string passed to ZoneInfo #114731
• [3.13] gh-114713: Handle case of an empty string passed to zoneinfo.ZoneInfo (GH-114731) #132563
• gh-114713: Handle case of an empty bytes object passed to zoneinfo.ZoneInfo #132582
• gh-114713: Revert gh-114731 #133330
• [3.13] gh-114713: Revert gh-114731 (GH-133330) #133331