Cleaning salsa build cache before a new build

[Vincent Danjean <vdanjean.ml@free.fr>]

  Hi,

  While packaging a new upstream version of one of my packages (taktuk),
I switched from getting hand-made source tarball (with "make dist" from autotools)
by the upstream developper to a tag in the git repo (for better tracability).
  Of course, I initially messed up and pushed to salsa a new upstream version
(in the pristine-tar branch) still coming from the hand-made tarball.

  Since, I fixed all of this. Now, the git on salsa (and the uploaded package) is
correctly using the tarball coming from git. It is also now correctly registered
in the pristine-tar of the git repo.

  My problem is that salsa-ci is still using the hand-made tarball. In the build log,
I can see:
[...]
$ if find . -maxdepth 3 -wholename "*/debian/source/format" -exec cat {} \; | grep -q '3.0 (gitarchive)'
gbp:info: All Orig tarballs 'taktuk_3.7.8.orig.tar.gz' found at '/builds/debian/taktuk/build/'
gbp:info: Creating taktuk_3.7.8.orig.tar.gz from 'upstream/3.7.8'
gbp:info: Disabling 'cleaner' hook
gbp:info: Exporting 'HEAD' to '/builds/debian/taktuk/build/taktuk-tmp'
gbp:info: Moving '/builds/debian/taktuk/build/taktuk-tmp' to '/builds/debian/taktuk/build/taktuk-3.7.8'
gbp:info: Performing the build
$ ls -lh ${BUILD_DIR}
total 608K
drwxrwxr-x 9 root root 4.0K Sep 30 08:47 taktuk-3.7.8
-rw-r--r-- 1 root root 603K Sep 30 08:50 taktuk_3.7.8.orig.tar.gz
[...]


The hand-made tarball is about 600k, the git tarball is about 150K
(no autotool auto-generated files), so salsa-ci is clearly using the
bad (previously used) tarball.

  Is there a way to remove the (cached on disk) tarball on salsa, so
that the correct tarball would be taken from pristine-tar git branch?

  Regards
    Vincent