pkg-merge-upstream-to-downstreams: Don't automerge on conflicts

Do not enable `merge_when_pipeline_succeeds` when the update pipeline
failed to merge and a MR with the unmerged branch is created.

Otherwise the MR will unexpectedly be merged immediately as soon as the
pipeline succeeds when someone pushes the manually resolved merge.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

package-source-builder/overlay/usr/bin/apertis-pkg-merge-upstream-to-downstreams

@@ -162,7 +162,7 @@ def main():
     ref = git("rev-parse", downstream_branch).rstrip()
     proposed_branch = f"proposed-updates/{upstream_branch}/{ref[0:8]}"
 
-    push_this_merge_request = partial(push_merge_request, args.project_url, proposed_branch, upstream_branch, downstream_branch, auto_merge, dry_run=args.dry_run)
+    push_this_merge_request = partial(push_merge_request, args.project_url, proposed_branch, upstream_branch, downstream_branch, dry_run=args.dry_run)
 
     # check if we have a proposed branch from a previous iteration
     if git("rev-parse", "--verify", proposed_branch, _ok_code=[0, 128]).strip():
@@ -177,7 +177,7 @@ def main():
       #    submit a MR from proposed-updates/debian/buster/badf00d
       #    to apertis/v2020
       print(f"Reusing branch {proposed_branch} to be merged into {downstream_branch}")
-      push_this_merge_request()
+      push_this_merge_request(auto_merge=auto_merge)
       continue
 
     git("branch", proposed_branch, upstream_branch)
@@ -185,6 +185,7 @@ def main():
     print(f"Attempt merging {upstream_branch} into {downstream_branch} via {proposed_branch}", flush=True)
     git("checkout", "--force", "-B", "tmp", downstream_branch)
     conflict = None
+    auto_merge_override = auto_merge
     try:
         apertis_pkg_merge_updates(f"--osname={osname}", f"--downstream={downstream_branch}",
                                   f"--upstream={upstream_branch}", f"--local-version-suffix={local_suffix}",
@@ -192,6 +193,7 @@ def main():
         git("branch", "--force", proposed_branch, "HEAD")
     except ErrorReturnCode:
         print(f"Failed to merge {upstream_branch} into {downstream_branch} via {proposed_branch}")
+        auto_merge_override = []
         conflict = Conflict(
             upstream_branch=upstream_branch,
             downstream_branch=downstream_branch,
@@ -207,7 +209,7 @@ def main():
           continue
 
     print(f"Submit {proposed_branch} for merging into {downstream_branch} the updates from {upstream_branch}")
-    push_this_merge_request()
+    push_this_merge_request(auto_merge=auto_merge_override)
 
   if conflicts:
     print("\n⚠️  Failed to automatically merge the updates below.")