Single digit id edge case
-------------------------

At one time, the code for retrieving the email address from the contact of the
saved student id (+ :n) would crash if the id was one in length and no ':n' was
spefified.  Here we make sure it is fixed.

First we need to set up the school.

    >>> from schooltool.app.browser.ftests import setup
    >>> setup.setUpBasicSchool()
    >>> manager = setup.logIn('manager', 'schooltool')

We'll create a student with a single-digit user id:

    >>> from schooltool.intervention.browser.ftests import ftests
    >>> ftests.addPerson('Single-digit', 'Single-digit', 's', 'pwd')

Going to their intervention center and clicking 'Add Message' no longer
crashes.

    >>> manager.getLink('Manage').click()
    >>> manager.getLink('Persons').click()
    >>> manager.getLink('Single-digit').click()
    >>> manager.getLink('Intervention Center').click()
    >>> manager.getLink('New Message').click()
    >>> analyze.printQuery("id('content-body')//input[@type='checkbox']", manager.contents)
    <input type="checkbox" name="person.s" />

