quilt 3.0 package without patches fails to build

[Christian Ehrhardt ]

Hi,
it seems on build-source there are too much implications on how patches will be applied.
For example the current ethtool is such a package.

It is quilt 3.0
It has no patches atm
It also has no .pc dir
neither gets a .pc created as it does have no patches

What happens is this:
$ mkdir /tmp/testgu
$ cd /tmp/testgu
$ git ubuntu clone ethtool
$ cd ethtool/
$ git checkout ubuntu/bionic
$ git ubuntu build-source --verbose --sign
02/23/2018 13:08:43 - DEBUG:Executing: git config gitubuntu.lpuser
02/23/2018 13:08:43 - DEBUG:Executing: grep -q "* -ident" /tmp/testgu/ethtool/.git/info/attributes
02/23/2018 13:08:43 - DEBUG:Executing: grep -q "* -text" /tmp/testgu/ethtool/.git/info/attributes
02/23/2018 13:08:43 - DEBUG:Executing: grep -q "* -eol" /tmp/testgu/ethtool/.git/info/attributes
02/23/2018 13:08:43 - DEBUG:Executing: git config gitubuntu.lpuser
02/23/2018 13:08:43 - DEBUG:Executing: sh -c "dpkg-parsechangelog -l- -n1 -SVersion"
02/23/2018 13:08:43 - DEBUG:Executing: git status --porcelain
02/23/2018 13:08:43 - ERROR:Unable to automatically determine importer branch: Multiple candidate branches found and they do not target the same series: pkg/ubuntu/bionic-proposed, pkg/ubuntu/bionic, pkg/debian/sid, pkg/debian/buster. Please pass --target-branch.
02/23/2018 13:08:43 - DEBUG:Executing: sh -c "dpkg-parsechangelog -l- -SSource"
02/23/2018 13:08:43 - DEBUG:fetch_orig_from_parent_dir(source=None) failed
02/23/2018 13:08:43 - DEBUG:fetch_orig_from_cache(source=ubuntu) failed
02/23/2018 13:08:43 - DEBUG:Executing: pristine-tar list
02/23/2018 13:08:43 - DEBUG:Executing: pristine-tar list
02/23/2018 13:08:43 - WARNING:No pristine-tar data found for 4.11
02/23/2018 13:08:43 - DEBUG:fetch_orig_from_pristine_tar(source=ubuntu) failed
02/23/2018 13:08:45 - DEBUG:Checking if upstream version of publish 1:4.11-1 matches 4.11
02/23/2018 13:08:45 - DEBUG:Upstream version of publish 1:4.11-1 matches
02/23/2018 13:08:47 - DEBUG:Verifying orig tarball /tmp/testgu/ethtool/.git/git-ubuntu-cache/ethtool_4.11.orig.tar.xz
02/23/2018 13:08:47 - DEBUG:Executing: sh -c "dpkg-parsechangelog -l- -SDistribution"
02/23/2018 13:08:47 - DEBUG:Caching dsc file
02/23/2018 13:08:47 - DEBUG:Executing: git worktree add --detach --force /tmp/tmpar_um8q0 HEAD
02/23/2018 13:08:47 - DEBUG:Executing: dpkg-source --print-format .
02/23/2018 13:08:47 - DEBUG:Executing: git worktree prune
02/23/2018 13:08:47 - DEBUG:Executing: git worktree add --detach --force /tmp/tmpwk67kuec 170f97a84b12d9ce10b757018abb6417a68d5dce
02/23/2018 13:08:47 - DEBUG:Executing: dpkg-source --print-format .
02/23/2018 13:08:47 - DEBUG:Executing: git worktree prune
02/23/2018 13:08:47 - DEBUG:Executing: tar -x --strip-components=1 -f /tmp/tmp7704t4ok/ethtool_4.11.orig.tar.xz
02/23/2018 13:08:47 - DEBUG:Executing: quilt --quiltrc - push -a
Traceback (most recent call last):
  File "/snap/git-ubuntu/360/bin/git-ubuntu", line 11, in <module>
    load_entry_point('gitubuntu==0.6.2', 'console_scripts', 'git-ubuntu')()
  File "/snap/git-ubuntu/360/lib/python3.6/site-packages/gitubuntu/__main__.py", line 243, in main
    sys.exit(args.func(args))
  File "/snap/git-ubuntu/360/lib/python3.6/site-packages/gitubuntu/buildsource.py", line 103, in cli_main
    default_rem_args=default_rem_args,
  File "/snap/git-ubuntu/360/lib/python3.6/site-packages/gitubuntu/build.py", line 707, in cli_main
    retry_backoffs=args.retry_backoffs,
  File "/snap/git-ubuntu/360/lib/python3.6/site-packages/gitubuntu/build.py", line 493, in main
    retry_backoffs,
  File "/snap/git-ubuntu/360/lib/python3.6/site-packages/gitubuntu/build.py", line 1221, in fetch_orig_and_build
    retry_backoffs,
  File "/snap/git-ubuntu/360/lib/python3.6/site-packages/gitubuntu/build.py", line 783, in do_build
    tree_hash = repo.quiltify_and_changelogify_tree_hash(commitish)
  File "/snap/git-ubuntu/360/lib/python3.6/site-packages/gitubuntu/git_repository.py", line 2463, in quiltify_and_changelogify_tree_hash
    quiltify_tree_hash = self._maybe_quiltify_tree_hash(commit_hash)
  File "/snap/git-ubuntu/360/lib/python3.6/site-packages/gitubuntu/git_repository.py", line 2253, in _maybe_quiltify_tree_hash
    regenerated_pc_path,
  File "/snap/git-ubuntu/360/usr/lib/python3.6/shutil.py", line 309, in copytree
    names = os.listdir(src)
FileNotFoundError: [Errno 2] No such file or directory: '.pc'