This is the db-contrib-tool ticket. There is a a corresponding resmoke ticket here:
We need to keep 4.0 downloads & testing since we have extended contracts for 4.0. We should have our tooling point to a permanent location for 4.0 binaries (ie: Switch to downloading from the push task instead of the compile task). This needs to be done in db-contrib-tool on 6.0 as well as setup-multiversion on 5.0.