Reuse the wrong date from git commit for the snapshot changelog entry
If the changelog contains an incorrect date, the lintian pipeline will pass on a wip or proposed branch. However, when the pipeline runs on an Apertis branch, it will fail due to a debian-changelog-has-wrong-day-of-week lintian warning.
When the pipeline runs on a wip or proposed branch, two entries are added to debian/changelog: a snapshot entry with a correct date generated by dch, and an OBS build entry with the same date as the snapshot entry. When the pipeline runs on an Apertis branch, only the OBS build entry is added with an incorrect date, which triggers a debian-changelog-has-wrong-day-of-week lintian warning. Since lintian checks only the latest entry in the changelog, this warning is emitted only on Apertis branches.
To ensure that lintian complains for wip or proposed branches, reuse the wrong date from git commit for the snapshot changelog entry.