urllib.request.pathname2url() raises on NTFS alternate data stream

[barneygale]

Bug report

Bug description:

On Windows, urllib.request.pathname2url() raises OSError when given a path with a colon in any position other than the second character. This excludes paths with NTFS alternate data streams, which are valid in other path-processing functions (e.g. in os.path and pathlib):

>>> from urllib.request import pathname2url
>>> pathname2url(r'C:\foo:bar')
OSError: Bad path: C:/foo:bar  # expected: ///C:/foo%3Abar
>>> pathname2url(r'foo:bar')
OSError: Bad path: foo:bar  # expected: foo%3Abar

CPython versions tested on:

CPython main branch

Operating systems tested on:

Windows

Linked PRs

• GH-126601: pathname2url(): handle NTFS alternate data streams #126760

[barneygale]

Suggest we wait for #120423 to be fixed before tackling this one, as the required changes touch the same lines of code.

[barneygale]

Fixed in 3.14, but not backported as it's a pretty rare bug.