This package uses git-buildpackage with pristine-tar.

Import a new upstream version with:

  $ gbp import-orig --pristine-tar --uscan

If the import fails with an error such as the following:

  uscan die: OpenPGP signature did not verify. at /usr/share/perl5/Devscripts/Uscan/Output.pm line 77.

That means that you have to update the upstream key file
debian/upstream/signing-key.asc. For example:

  $ gpg --armor --export C60CFE9F27405101D06DE3B86D8D01ADE253B252 > debian/upstream/signing-key.asc

Create a pbuilder environment suitable for gbp:

  $ DIST=sid ARCH=amd64 git-pbuilder create

Build the package:

  $ DIST=sid ARCH=amd64 gbp buildpackage -jauto -us -uc --git-builder=git-pbuilder --changes-option=-S

Sign it:
  $ debsign systemtap_${VERSION}_source.changes
