buildrpm: enable to start the script from anywhere
Previously the script worked only from the hg root.
buildrpm: build from working dir parent and use hg version for RPM versioning
Previous, RPMs was always built from tip, and the release number did not match
the 'hg version' put in place for 1.4.
This will enable also to this script to be able to build official tag and not
only nightly build.
setup: fix
f51d1822d6fd refactoring, propagate env to runcmd