Seems to think an existing executable file doesn't exist

[dabrahams]

This commit works around a bug by not asking for the size of an existing executable file. The bug apparently makes FileManager().attributesOfItem(atPath:) throw error 260 for some accessible, existing files. Before that commit, when running swift build --build-tests in the right circumstances, the following occurs.

executing task: /usr/bin/swift build --build-tests 

error: Error Domain=NSCocoaErrorDomain Code=260 "The file doesn’t exist."
error: build stopped due to build-tool plugin failures

In my experience, this reproduces only in a devcontainer running on Intel hardware (can't reproduce on Apple Silicon). You can see it in GitHub CI for the reproducer project (if GitHub logs are out-of-date, make your own fork in GitHub and enable Actions) or you can run the devcontainer locally on your mac: install Docker and Visual Studio Code, open the project's root directory in VSCode and accept VSCode's suggestion to reopen the project in a devcontainer, then run the tests.

The GitHub CI logs from before and after the commit in question are
devcontainer-log-before.txt
devcontainer-log-after.txt