The subprocess module has been unused since 400066ea
(daklib/rm.py: format date in python).

Fixes:

    daklib/architecture.py:113: SyntaxWarning: "is" with a literal. Did you mean "=="?

with Python >= 3.8.

It looks like some removal records had trailing whitespace which
confuses users of the deb822 file.

Reference: https://bugs.debian.org/960504

This reverts commit e43911e2.

* pr-200:
  dak rm: allow removal of binaries without source

* pr-199: (44 commits)
  Always run python3 tests, they succeed now.
  ci: remove stretch tests
  test 2001-cruft: add cruft report
  test 2000-dinstall: run make-changelog
  Add test 0006-dm-commands
  Testsuite fixtures: change some uploaders and add extra package
  tests: 2003-c-s-propup: remove first dinstall call
  test 0005-encoding: add extra checks
  integration-tests: add check_output function
  run-ci: don't run 2to3, it's not needed anymore
  run-ci: add annotated coverage report
  gitlab-ci: coverage job only uses py2 data
  integration-tests/dak-coverage.sh: fix coverage when working dir changes
  integration-tests/common: add function to save ci artifacts
  run-ci: define DAK_CI_OUTPUT_DIR
  daklib/dbconn.py: use textutils.force_to_utf8 for contents filename
  daklib/utils.py: handle encoding in gpg_get_key_addresses using six
  daklib/checks.py: use six function in check_fields_for_valid_utf8
  daklib/dbconn.py: set database connection to utf-8 for python3
  load_keys: make sure data from gpg is str
  ...

* utf8-filenames:
  For FTP auto rejection of non UTF-8 filenames, add a renamed Lintian tag but retain the old one.

When removing binaries from a source, do the removal, even if the source is
not in the suite.

Normally, if a binary is in the suite, the source of that binary should also
be in the suite. However, it seems that this is not always the case. As an
example, some binaries that were prop-uped into unstable don't seems to have
the corresponding source in unstable.

This change allow dak rm to remove these binaries.

The unit tests are run together with the other tests, so we don't need
to run them separately anymore.

We're not running stretch anymore. Also, some of the six functions are
not available on stretch.

This test was also renamed from 2001-nviu.

Test dm acls and commands.

Re-use most of the existing packages, but change the uploader for the dm
test. For the other tests, all keys are treated as DDs, so it doesn't
change anything.

This test is the longest in the testsuite. The dinstall call for the
empty archive already runs in other tests, and removing it doesn't
affect the rest of the test.

- run make-maintainers
- run queue-report
- add rdep check to dak rm
- test sending mail
- run show-new
- run check in process-new

Avoids failure if the py3 job is manually started.

This change should work in both python2 and python3.

Handle all data as str() in the functions that generate the data.

All functions in examine_package now return data, instead of writing it
themselves.

Don't replace stdout with the less fd, but write directly to less in
examine_package and process_new.

Force all output to less to be binary using six (which always uses
utf-8).

Dxplicitly open file as binary in strip_pgp_signature.

Write the html output to file as text in show_new.