v1.3.0rc1 bug fix: skipsteps in regtester

Fix for `skipsteps` being ignored in `regtest` function that takes control over each of the steps by itself, causing `OpenBLAS` and `numactl` builds to fail.

This, once again, shows that we need to take care of this split-brain situation, see #502.

Note: this doesn't affect the framework itself, only the `--regtest` command line option.