@Nullable
  private static GitRevisionNumber findOriginalRevisionNumber(@NotNull Project project,
                                                              @NotNull VirtualFile root,
                                                              @Nullable VcsRevisionNumber yoursRevision,
                                                              @Nullable VcsRevisionNumber theirsRevision) {
    if (yoursRevision == null || theirsRevision == null) return null;
    try {
      return GitHistoryUtils.getMergeBase(project, root, yoursRevision.asString(), theirsRevision.asString());
    }
    catch (VcsException e) {
      LOG.warn(e);
      return null;
    }
  }
@Nullable
  private static GitRevisionNumber findOriginalRevisionNumber(@NotNull Project project,
                                                              @NotNull VirtualFile root,
                                                              @Nullable VcsRevisionNumber yoursRevision,
                                                              @Nullable VcsRevisionNumber theirsRevision)