I was running mk-origtargz to get it to rename my files for me, with
this rune:

    mk-origtargz --rename --package inkscape -v 1.0~beta1 \
        --signature-file inkscape-1.0beta1.tar.bz2.sig --signature 1 \
        inkscape-1.0beta1.tar.bz2

And expected it to be lighting fast, since it would only:
 1. rename the tarball
 2. re-export the signature, since it was a binary one

However, I saw it taking several seconds, and when looking at the
process list I noticed a `bzip2` on top.  So, I believe it was
decompressing the tarball.

I see no reason to do this in such case, so it really shouldn't be.

On that note, I wonder if it shouldn't also be logging when it starts to
decompress a tarball, since it's an operation that can easily take
minutes for large ones.