tests: Unset SOURCE_DATE_EPOCH
Some distributions set this during build in order to have reproducible
builds from the same source code: for example, Debian uses the date
from debian/changelog.
However, some of our tests assume that `ostree commit` will result in
a commit with the current date/time, and SOURCE_DATE_EPOCH breaks that
assumption. Unset it for our build-time tests.
Bug: https://github.com/ostreedev/ostree/issues/2405
Signed-off-by: Simon McVittie <smcv@collabora.com>
Applied-upstream: 2021.4, commit:
2c5fa2cdb6c304394ca629c959ec53d878f3f93a
Gbp-Pq: Name tests-Unset-SOURCE_DATE_EPOCH.patch