test suite: Test dgit calling git-debrebase on new debianisation

test suite: Test dgit calling git-debrebase on new debianisation

Now all the cases in dgit's branch_is_gdr history walker are tested:

  DGIT_TEST_DEBUG=-DD tests/using-intree tests/run-all
  cat tests/tmp/*.log |perl -ne 'next unless s/^branch_is_gdr  \w+ //; print' |sort -u |less

Produces the same list as:

  git-grep 'branch_is_gdr  ' | perl -pe 's/^^dgit:\s+//' |sort |less

(With the list of gdr commit annotations the same as in the source.)

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>