mrhlpr: use Part-of trailer instead of adding MR ID to subject

We are planning to migrate to marge-bot for handling merging commits, and with it adopt a new way of linking commits to their source MRs.

Using a trailer with Part-of: !MR-ID results in the commits being linked to the MR, and the GitLab web interface inserting a hyperlink in its place making it easier to jump to the source MR.

Let's adopt this for MRs we still merge manually now.

Use the full URL to the MR rather than just the ID, this way if we ever split or merge repos it will still be easily possible to trace commits back to their original MRs.

Signed-off-by: Caleb Connolly caleb@postmarketos.org

mrhlpr/data/msg_filter_add_commit_id.py

@@ -16,22 +16,43 @@ if not mrhlpr_msg_filter_mr_id:
     exit(1)
 
 
-line_number = 0
-suffix = " (MR " + mrhlpr_msg_filter_mr_id + ")"
+line_count = 0
+empty_lines = 0
+trailer = f"Part-of: {mrhlpr_msg_filter_mr_id}"
+emit_trailer = True
+have_trailers = False
 for line in sys.stdin:
     line = line.rstrip()
-    line_number += 1
+    line_count += 1
 
-    # Add the suffix in the first line
-    if line_number == 1:
-        if line.endswith(suffix):
-            print(line)
-        else:
-            print(line + suffix)
+    # Don't emit the trailer if the commit already has it
+    if line == trailer:
+        emit_trailer = False
     else:
-        # Make sure we have an empty line after the first one
-        if line_number == 2 and line != "":
-            print()
+        # Count empty lines since the last non-empty line
+        if line == "":
+            empty_lines += 1
+        else:
+            empty_lines = 0
+
+        if any(
+            line.lower().startswith(prefix)
+            for prefix in [
+                "signed-off-by: ",
+                "co-developed-by: ",
+                "suggested-by: ",
+                "reported-by: ",
+                "change-id: ",
+                "co-authored-by: ",
+                "part-of: ",
+            ]
+        ):
+            have_trailers = True
+
+    print(line)
 
-        # Print all other lines without modification
-        print(line)
+if emit_trailer:
+    # Print a blank line before the trailer section unless we already have trailers
+    if empty_lines == 0 and not have_trailers:
+        print()
+    print(trailer)