pkg-merge-upstream-to-downstreams: Add --dry-run

Add a command line flag to avoid pushing commits, to make local testing easier.

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

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

@@ -10,6 +10,7 @@
 import argparse
 from sh.contrib import git
 from sh import apertis_pkg_merge_updates
+from sh import echo
 import re
 from pathlib import Path
 from functools import partial
@@ -53,16 +54,16 @@ def is_minor_change(upstream, downstream):
   o = git('diff', '--exit-code', upstream, downstream, ':!debian/changelog', ':!debian/apertis/*', _ok_code=[0,1])
   return o.exit_code == 0
 
-def push_merge_request(project_url, proposed_branch, upstream, downstream, auto_merge = ''):
+def push_merge_request(project_url, proposed_branch, upstream, downstream, auto_merge = '', dry_run=False):
   title = f"Update from {upstream} for {downstream}"
   print(f"Pushing {proposed_branch}: {title}")
 
   print(f'Minor change {upstream}..{proposed_branch}? {is_minor_change(upstream, proposed_branch)}')
 
-  git_push_custom = git.push.bake()
+  git_push_custom = echo.bake("dry run:", "git", "push") if dry_run else git.push.bake()
   if is_minor_change(upstream, proposed_branch) and downstream in auto_merge:
     print('Minor change and auto_merge set, merge can be done when pipeline succeeds')
-    git_push_custom = git.push.bake('-o', 'merge_request.merge_when_pipeline_succeeds')
+    git_push_custom = git_push_custom.bake('-o', 'merge_request.merge_when_pipeline_succeeds')
   else:
     print('Merge should be reviewed')
 
@@ -86,6 +87,7 @@ def main():
   parser.add_argument('project_url', type=str, help='git project url to push updates to')
   parser.add_argument('--auto-merge', dest='auto_merge', type=str, default='',
                       help='list of branches that allow auto merge, colon-separated (e.g.  apertis/v2020dev0:apertis/v2019)')
+  parser.add_argument('--dry-run', action='store_true', help='do not push merged commits')
   args = parser.parse_args()
 
   upstream = args.upstream
@@ -111,7 +113,7 @@ 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)
+    push_this_merge_request = partial(push_merge_request, args.project_url, proposed_branch, upstream_branch, downstream_branch, auto_merge, 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():