git: handle archive generation crash case when submodules are present.

vcsserver/git.py

@@ -1241,7 +1241,10 b' class GitRemote(RemoteBase):'
                     file_path = fn.path
                     mode = fn.mode
                     is_link = stat.S_ISLNK(mode)
-                    yield ArchiveNode(file_path, mode, is_link, repo[fn.id].read_raw)
+                    if mode == pygit2.GIT_FILEMODE_COMMIT:
+                        log.debug('Skipping path %s as a commit node', file_path)
+                        continue
+                    yield ArchiveNode(file_path, mode, is_link, repo[fn.hex].read_raw)
 
         return archive_repo(file_walker, archive_dest_path, kind, mtime, archive_at_path,
                             archive_dir_name, commit_id)