### Please describe the problem.

The naming conventions for adjusted branches are poorly chosen (adjusted/master(unlocked) or adjusted/master(hidemissing)).  The parentheses cause problems when checking out the branch without protecting the name by way of quotation marks.  This problem is exacarbated at least on my Ubuntu Focal system by the fact that the provided bash-completion completes the branch name without those marks.

### What version of git-annex are you using? On what operating system?
8.20200226-1 on Ubuntu Focal

### What steps will reproduce the problem?

    git annex adjust --hide-missing 
    git checkout master
    #git checkout adjTABusted/master(hidemissing)
    git checkout adjusted/master(hidemissing)

Result:

    $ git checkout adjusted/master(hidemissing) 
    bash: syntax error near unexpected token `('
    $ git checkout "adjusted/master(hidemissing)"
    Switched to branch 'adjusted/master(hidemissing)'

The problem is easy to fix, I think, by choosing a different naming convention. I'm not sure how to deal with legacy-named branches going forward, though.

Thank you very much for making git-annex available, much appreciated.
