Bug fix: Preventing infinite loop after installing a native dependency package.

Currently "tpkg --upgrade" falls in an infinite loop after installing a native dependency package.

This can happen when a new version of a tpkg package introduces a new native dependency.
Then, the first upgrade attempt always gets stuck.
The second attempt will succeed since the required native package was installed during the first attempt.
However, this gets worse if the first attempt was made from a daemon(e.g. Etch), which will continue to run calculating the tpkg checksum(hash) over and over again wasting significant CPU time.

Jae Park