private void abortOnMultiplePulledHeads(List<HgRevisionNumber> newBranchHeadsAfterPull) throws VcsException {
    if (newBranchHeadsAfterPull.size() != 1) {
      throw new VcsException(HgBundle.message("hg4idea.update.error.merge.multipleRemoteHeads", newBranchHeadsAfterPull.size(),
                                              repoRoot.getPath()));
    }
  }
private void abortOnMultiplePulledHeads(List<HgRevisionNumber> newBranchHeadsAfterPull)