Handle missing Python executable in ImageShow on macOS

[bryant1410]

There are exceptional cases in which sys.executable is empty or null (see the docs). I think it's better to just not delete the image in these cases, instead of crashing.

[radarhere]

Just curious - did you figure this out because you are in an environment where sys.executable is None? What type of environment is that?

[bryant1410]

Yes. I'm not sure how much details I can share, but it's kind of a custom way of running Python where the final program is compiled, so there's no Python interpreter anymore (AFAIK).

What about calling os.remove directly?

[radarhere]

The subprocess doesn't just call os.remove, it also calls time.sleep(20). This behaviour started in #6010, so that the current Python process doesn't hang for 20 seconds. This period is intended to give time for Preview to open the image.

However, given that #6045 dropped removing the image altogether on Unix, the current form of this PR is not unreasonable.

[radarhere]

I've created bryant1410#1 as a suggestion - if sys.executable is not available, how about falling back to python3 instead?

[bryant1410]

Sounds good to me! It works locally. I merged it so it's here.

[beaux-riel]

I’m still experiencing the issue where the temporary file is deleted before Preview can open it on Mac. Has/will this be resolved?

[radarhere]

This PR hasn't been released yet. It will be released as part of Pillow 9.3.0, due out towards the end of October.

However, it doesn't sound like you're experiencing the same problem. Are you saying that your images are taking longer than 20 seconds to open in Preview? Are they very large?