@Override
  public ContentRevision createFileContent(VcsRevisionNumber revisionNumber, VirtualFile file) {
    if (file == null) {
      return null;
    }

    VirtualFile vcsRoot = VcsUtil.getVcsRootFor(project, file);
    if (vcsRoot == null) {
      return null;
    }

    HgRevisionNumber hgRevisionNumber = (HgRevisionNumber) revisionNumber;
    if (hgRevisionNumber.isWorkingVersion()) {
      throw new IllegalStateException("Should not compare against working copy");
    }
    HgFile hgFile = new HgFile(vcsRoot, HgUtil.getOriginalFileName(VcsUtil.getFilePath(file), ChangeListManager.getInstance(project)));
    return HgContentRevision.create(project, hgFile, hgRevisionNumber);
  }
@Override
  public ContentRevision createFileContent(VcsRevisionNumber revisionNumber, VirtualFile file)