pkg-merge: Always submit a new MR, even with conflicts

Create a MR even when the local attempt to merge failed. In that case let the proposed updates branch point to the upstream branch and create a MR to submit it to the downstream branch.

This makes the failed updates more visbile and easier to track than the failed pipelines.

Task: T7797

added 8 commits

• 788aa27a - Debian commits
• d285422a - Enable only the package-source-builder docker image
• 008b0196 - Use CUSTREL for the custom release string
• 8ec55ede - Set CUSTREL to v2022dev2
• b26ad3fa - Explicitly set TAG to latest
• ea996247 - Add the missing type specifier
• 82b4d125 - apertis-pkg-merge-upstream-to-downstream: Rework the code
• 6620e986 - apertis-pkg-merge-upstream-to-downstreams: Always create MR

Compare with previous version

changed target branch from apertis/v2022dev1 to apertis/v2022dev2

mentioned in merge request !183 (merged)

Fails on https://gitlab.apertis.org/pkg/fscrypt/-/jobs/842992 with:

Traceback (most recent call last):
  File "/usr/bin/apertis-pkg-merge-upstream-to-downstreams", line 130, in <module>
    main()
  File "/usr/bin/apertis-pkg-merge-upstream-to-downstreams", line 89, in main
    if git("merge-base", "--is-ancestor", upstream_branch, downstream_branch, _ok_code=[0,1]).exit_code == 0:
  File "/usr/lib/python3/dist-packages/sh.py", line 1520, in __call__
    return RunningCommand(cmd, call_args, stdin, stdout, stderr)
  File "/usr/lib/python3/dist-packages/sh.py", line 784, in __init__
    self.wait()
  File "/usr/lib/python3/dist-packages/sh.py", line 841, in wait
    self.handle_command_exit_code(exit_code)
  File "/usr/lib/python3/dist-packages/sh.py", line 865, in handle_command_exit_code
    raise exc
sh.ErrorReturnCode_128: 
  RAN: /usr/bin/git merge-base --is-ancestor debian/bullseye apertis/v2022dev2
  STDOUT:
  STDERR:
fatal: Not a valid object name apertis/v2022dev2

added 3 commits

• 5d3809f1 - pkg-merge-upstream-to-downstreams: Ensure local downstream branch is created
• cb20053f - pkg-merge-upstream-to-downstream: Streamline the loop
• 6a930bef - pkg-merge-upstream-to-downstreams: Always create MR, even with conflicts

Compare with previous version

added 2 commits

• 5e3ffb23 - pkg-merge-upstream-to-downstream: Streamline the loop
• dc1cf954 - pkg-merge-upstream-to-downstreams: Always create MR, even with conflicts

Compare with previous version

resolved all threads

Unintentionally tested on https://gitlab.apertis.org/pkg/fscrypt/-/jobs/843153

b26ad3fa causes every branch to override the latest Docker image, so all the artifacts produced here ended up directly in production... :)

merged