dependencies: pin venusian

dependencies: bumped not pinned dependency venusian to 1.2.0

dependencies: bumped not pinned dependency pluggy to 0.8.1

dependencies: bumped evolve to 8.3.3 version.

subprocession: limit fd leaks

hooks: expose logic to fetch hook file information.

git: use iterative fetch to prevent errors about too many arguments on very large repositories.

exception: store orginal tb and exc inside the new exception passed to rhodecode from vcsserver.

docs: updated copyrights to 2019

dependencies: bumped subprocess32 to 3.5.3