Removes paket bootstrap executable from PaketBootstrap task outputs

[Joaquimmnetto]

Description

Fixes a bug detected in UBS, where gradle deletes the paket.bootstrap.exe file generated by the DownloadPaketBootstraper.

You can reproduce the issue by calling:

gradlew paketBootstrap #this should run correctly
rm -r .paket
gradlew paketBootstrap #this should fail, accusing that the `paket.bootstrap.exe` file doesn't exists.
# After this, subsequent calls to `paketBootstrap` works as it should, until you delete the `.paket` folder again. 

Several tests pointed out that the file is correctly downloaded, but just disappears between the DownloadPaketBootstraper and PaketBootstrap tasks. This happens because its set as an output of PaketBootstrap. Then in some conditions, gradle wipes out the file, likely to make room to some intended output, making the PaketBoostrap task fail. Removing the bootstrap executable from the outputs of PaketBootstrap solves the issue, and does not generate any side effects.

Changes

• paket.bootstrap.exe file missing when .paket folder is removed.

[Azurelol]

Thank you!