private @Nullable String tryFindRebaseBranch() {
    String currentBranch = readRebaseDirBranchFile(myGitFiles.getRebaseApplyDir());
    if (currentBranch == null) {
      currentBranch = readRebaseDirBranchFile(myGitFiles.getRebaseMergeDir());
    }
    return (currentBranch == null || currentBranch.equals(DETACHED_HEAD)) ? null : currentBranch;
  }
private @Nullable String tryFindRebaseBranch()