Fix tool cargo being off-by-one from rustc staging

Previously if you pass compiler stage 1 to `tool::Cargo`, it will build
stage2 rustc and give you back a cargo built with stage2 rustc, which is
not what we want.

This commit adds a hack that chops off a stage from the compiler passed
to `tool::Cargo`, meaning that we will get a cargo built with stage 1
compiler, avoiding unnecessary and incorrect build of stage2 rustc and
the cargo built by that.

0 files changed, 0 insertions, 0 deletions