swift-run crashes when using the swiftbuild build system

[dschaefer2]

Is it reproducible with SwiftPM command-line tools: swift build, swift test, swift package etc?

• Confirmed reproduction steps with SwiftPM CLI. The description text must include reproduction steps with either of command-line SwiftPM commands, swift build, swift test, swift package etc.

Description

Under debug I can see that the build service thread is still running when swift-run closes all the file handles before doing the exec call to launch the executable. I can see why we need to do that to make sure we aren't leaking file descriptors there. But we should probably wait until the build service is fully shut down before doing that.

Expected behavior

No response

Actual behavior

No response

Steps to reproduce

No response

Swift Package Manager version/commit hash

No response

Swift & OS version (output of swift --version ; uname -a)

This is off the initial PR for the swiftbuild integration.

[dschaefer2]

This is with a project created with swift package init --type executable.