97         revision = None
101                 revision = project.get('revision')
103         return revision
105     def _check_revision_exists(self, revision, git_project_path):  argument
114         def _check_rev_list(revision):  argument
118                 rev=revision, proj=git_project_path))
121                     'git', '-C', path, 'rev-list', 'HEAD..{}'.format(revision)
136                             rev=revision, proj=git_project_path))
139         def _get_2nd_parent_if_merge_commit(revision):  argument
148                 format(rev=revision, proj=git_project_path))
152                     '{}^2'.format(revision)]
158                         rev=revision, remote=self._remote_git, err=error))
160                     'in the current branch'.format(revision))
165         if _check_rev_list(revision):
174             cmd = ['git', '-C', path, 'fetch', self._remote_git, revision]
180                     rev=revision, remote=self._remote_git, err=error))
184         parent_revision = _get_2nd_parent_if_merge_commit(revision)
228                 revision = self._get_revision(module_path, manifest_projects)
229                 if not revision:
234                     revision, module_path)