Bootstrapper failed without exit code

Description & Repro

In FAKE we use

    Paket.Push(fun p ->
        { p with
            DegreeOfParallelism = 2
            WorkingDir = nugetLegacyDir })

Apparently this fails when using magic mode in combination with a not downloaded release (IE just increasing version in paket.dependencies).
Note that you SHOULD not run FAKE with build.sh and build.cmd as those will download paket and workaround the issue

1. Increase version in paket.dependencies

2. run a FAKE target with the above code && have at least 2 packages to push in the folder

Expected behavior

Successful push of all the packages

Actual behavior

NO error, following in stdout:

The process cannot access the file 'C:\Users\matth\.babun\cygwin\tmp\paket_4129425AFDA0D8826014E424D06C0EB7A734D935EB438ED99CC404FD8F885AF7.exe' because it is being used by another process. (Github - cached)

And only ONE of the first TWO packages pushed (one is missing).

Known workarounds

run paket.exe --version before running FAKE.

Remarks

Imho this should not happen with current projects a lot as bootstrapping process usually will have paket downloaded. But it might be a problem with FAKE 5 in the described situation.
Problem is that at the very least the build needs to break. Otherwise people won't notice that paket has done nothing (in this case a package has not been pushed!). I guess paket-bootstrapper returns an incorrect exit-code in magic mode in this error condition.

Start with the paket-bootstrapper path used by FAKE magic mode and reproduce the issue by increasing the version in paket.dependencies without first running paket.exe --version. Check the behavior around the temporary paket_*.exe and the build.sh/build.cmd workaround; done means the failure returns a nonzero exit code and all packages are pushed.