contrib/packagelib.sh

setup: use try/except/finally

This will raise a syntax error for people who attempt to use Py2.4,
but that's already going to fail and we have no way to keep other
2.6isms from creeping in since we've removed the check-code rules and
the buildbot.

gethgversion() {
    make clean
    make local || make local PURE=--pure
    HG="$PWD/hg"

    $HG version > /dev/null || { echo 'abort: hg version failed!'; exit 1 ; }

    hgversion=`$HG version | sed -ne 's/.*(version \(.*\))$/\1/p'`

    if echo $hgversion | grep -- '-' > /dev/null 2>&1; then
        # nightly build case, version is like 1.3.1+250-20b91f91f9ca
        version=`echo $hgversion | cut -d- -f1`
        release=`echo $hgversion | cut -d- -f2 | sed -e 's/+.*//'`
    else
        # official tag, version is like 1.3.1
        version=`echo $hgversion | sed -e 's/+.*//'`
        release='0'
    fi
}