ciq-cherry-pick.py: Drop git's conflict comment block from MERGE_MSG

When a cherry-pick hits a conflict, git appends a comment block to
MERGE_MSG ("# Conflicts:" followed by the conflicted paths).
manage_commit_message() reads MERGE_MSG, inserts the CIQ header block,
and writes the whole thing back, conflict comments included. The script
then exits telling the user to resolve the conflict and commit, and
committing with -F keeps those lines, since -F's default cleanup mode
only strips whitespace, not comments. The conflict block winds up in the
final commit message verbatim.

Fix it by dropping the tail of the message starting at the
"# Conflicts:" line before standardizing. Only the trailing
git-generated block goes; legitimate body lines starting with "#"
earlier in the message survive.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: 2 people

ciq-cherry-pick.py

@@ -179,6 +179,14 @@ def manage_commit_message(full_sha, ciq_tags, jira_ticket, commit_successful):
     except IOError as e:
         raise RuntimeError(f"Failed to read commit message from {MERGE_MSG}: {e}") from e
 
+    # git appends a "# Conflicts:" comment block to MERGE_MSG on a conflicted
+    # cherry-pick, and committing with -F doesn't strip comment lines. Drop the
+    # block to keep it out of the final commit message.
+    for i, line in enumerate(original_msg):
+        if line.rstrip("\n") == "# Conflicts:":
+            original_msg = original_msg[:i]
+            break
+
     optional_msg = "" if commit_successful else "upstream-diff |"
     new_msg = CIQ_cherry_pick_commit_standardization(
         original_msg, full_sha, jira=jira_ticket, tags=new_tags, optional_msg=optional_msg