The py.exe launcher cannot locate installations from the Store (unless you have no other installations on your machine, which is unlikely).

I added an "exe_display" override for listing paths, since the full path to the store app is not supposed to be used by users (it's different from sys.executable) and is only going to work when the shorter name is on PATH anyway (due to a limitation in Windows that I'm still trying to get fixed).

I also enabled support for the ExecutablePath key, which has the added benefit of making the debug py_d.exe able to find release Python 3.5+ installs (as well as finding the Store install at all, which is now using python3.8.exe as the main file because of the limitation I mentioned above).

Sample output after this change (some paths elided):

Installed Pythons found by ...\py.exe Launcher for Windows
(venv) C:\...\env\Scripts\python.exe *
-3.8-64 python3.8.exe
-3.7-32-32 C:\Python37_x86\python.exe
-3.7-64 C:\Python37_x64\python.exe
-3.6-32-32 C:\Python36_x86\python.exe
-3.6-64 C:\Users\...\AppData\Local\Programs\Python\Python36\python.exe
-3.5-32-32 C:\Python35_x86\python.exe
-3.5-64 C:\Python35_x64\python.exe
-3.4-64 C:\Python34_x64\python.exe
-3.3-64 C:\Python33_x64\python.exe
-3.3-32 C:\Python33_x86\python.exe
-3.2-64 C:\Python32_x64\python.exe
-3.2-32 C:\Python32_x86\python.exe
-3.1-64 C:\Python31_x64\python.exe
-3.1-32 C:\Python31_x86\python.exe
-3.0-32 C:\Python30_x86\python.exe
-2.7-64 C:\Python27_x64\python.exe
-2.7-32 C:\Python27_x86\python.exe
-2.6-32 C:\Python26_x86\python.exe
-2.5-32 C:\Python25_x86\python.exe

-3.7-32-32 C:\Python37_x86\python.exe
-3.6-32-32 C:\Python36_x86\python.exe
-3.5-32-32 C:\Python35_x86\python.exe

MAX_VERSION_SIZE was increased, so the INSTALLED_PYTHON version string is now the full registry key name with the "-32" suffix. If that's intentional, you'll have to account for it in show_python_list. But I don't think the "-32" suffix belongs in the version string.

Ah, good catch, I didn't notice that.

Because those are special cases, we should strip it off the version string. One day when we implement PEP-514 properly then they'll come back (and we'll probably drop the -64 suffix for consistency with the PEP).

New changeset ed93a88 by Steve Dower in branch 'master':
bpo-38133: Allow py.exe launcher to locate installations from the Microsoft Store (GH-16025)
ed93a88

New changeset 664d56a by Miss Islington (bot) in branch '3.8':
bpo-38133: Allow py.exe launcher to locate installations from the Microsoft Store (GH-16025)
664d56a

New changeset 4d20228 by Steve Dower in branch 'master':
bpo-38133: Update docs to reflect fixes to py.exe launcher (GH-16791)
4d20228

New changeset 42308e8 by Miss Islington (bot) in branch '3.8':
bpo-38133: Update docs to reflect fixes to py.exe launcher (GH-16791)
42308e8