Exact build process

Here's the latest commands necessary to build kotlin/gradle (after sbuild-debian-developer-setup):

mkdir kotlin
cd kotlin
git clone git@salsa.debian.org:samyak-jn/kotlin.git
git clone git@salsa.debian.org:samyak-jn/kotlin-deps.git
cd kotlin-deps/build-deps/
curl -O https://snapshot.debian.org/archive/debian/20201202T151734Z/pool/main/o/openjdk-8/openjdk-8-jre-headless_8u275-b01-1_amd64.deb
curl -O https://snapshot.debian.org/archive/debian/20201202T151734Z/pool/main/o/openjdk-8/openjdk-8-jdk-headless_8u275-b01-1_amd64.deb
cd ../../kotlin/
gbp buildpackage --git-ignore-branch --git-builder=sbuild --extra-package=../kotlin-deps/build-deps/ --add-depends=libkotlin-bootstrap-java

kotlin_1.3.31-1_amd64-2021-04-02T17_55_41Z.build

rm ../kotlin-deps/build-deps/libkotlin-bootstrap-java_0.0.0-1_all.deb
cp ../kotlin_1.3.31*_all.deb ../kotlin-deps/build-deps/
git checkout stage2 # this branch gets rebased and force pushed rather than merged
gbp buildpackage --git-ignore-branch --git-builder=sbuild --extra-package=../kotlin-deps/build-deps/ --add-depends=kotlin

kotlin_1.3.31-1_amd64-2021-04-02T18_39_30Z.build