import-debian-package: avoid oversized commit messages

gbp import-dsc puts all the new changelog entries in the commit message, generating big walls of text when, for instance, importing a new package for the first time. GitLab then puts the whole log message in the CI_COMMIT_MESSAGE env var, which makes the runner to fail during the executor preparation section with the error:

exec /usr/bin/dumb-init: argument list too long

See: https://gitlab.com/gitlab-org/gitlab/-/issues/392406

To avoid that, trim the message to only keep the first line.

Fix: infrastructure/apertis-issues#395 (closed)

debian/changelog

+apertis-dev-tools (0.2023.10) apertis; urgency=medium
+
+  * import-debian-package: avoid oversized commit messages
+    `gbp import-dsc` puts all the new changelog entries in the commit
+    message, generating big walls of text when, for instance, importing a new
+    package for the first time.
+    GitLab then puts the whole log message in the `CI_COMMIT_MESSAGE` env
+    var, which makes the runner to fail during the executor preparation
+    section with the error:
+        exec /usr/bin/dumb-init: argument list too long
+    To avoid that, trim the message to only keep the first line.
+
+ -- Dylan Aïssi <dylan.aissi@collabora.com>  Thu, 28 Sep 2023 16:02:24 +0200
+
 apertis-dev-tools (0.2023.9) apertis; urgency=medium
 
   * ade: Turn all from_* methods into proper classmethods