Windows py launcher: older 32-bit versions not supported in some cases

[boimart1]

Bug report

On 64-bit Windows, if both Python 2.7 32-bit and Python 2.7 64-bit are installed, these two installs are considered equivalent and only the 64-bit version is considered, both when running py -2-32 (which fails) and py -0 (which only displays the 64-bit version).

This is also the case for Python 3.4 and lower, as the "-32" suffix is only part of the tag in the registry in 3.5+.

Under C:\:

py -0p output:

While these versions are no longer officially supported since 2020, PEP-514 does have a section on backwards compatibility, mentioning:

To ensure backwards compatibility, applications should treat environments listed under the following two registry keys as distinct, even when the Tag matches:

HKEY_LOCAL_MACHINE\Software\Python\PythonCore\<Tag>
HKEY_LOCAL_MACHINE\Software\Wow6432Node\Python\PythonCore\<Tag>

Your environment

• CPython versions tested on: 3.11.1
• Operating system and architecture: Windows 10 x64

Linked PRs

• gh-101135: Windows launcher: Add backwards compatibility for older 32-bit versions #101138
• [3.11] gh-101135: Add backwards compatibility to Windows launcher for older 32-bit versions (GH-101138) #101290

[boimart1]

Note that I currently have a fix on the way, which also fixes some related issues in the way the EnvironmentInfo tree is handled.