The Debian build script outputs incorrect log messages when using PKG_PATH option

[zenmonkeykstop]

The scripts/build-debianpackage script can be used in two ways:

• if the PKG_PATH env var is set, it will attempt to build a debian package from either a source tree or a source tarball at the location in PKG_PATH, using the latest changelog entry to set the package version
• if PKG_PATH is not set, but PKG_VERSION is set, it will attempt to checkout and verify a production-signed tag $PKG_VERSION and build the debian package from the tagged source.

In recent builds, it came to light that even if it was invoked with PKG_PATH, the script will still set PKG_VERSION using the latest tag and either fail if that tag is not production-signed, or just use PKG_VERSION erroneously in messages instead of the actual version as pulled from the changelog.

This causes confusion, and delay.