Revert "Remove 'skip' decorator from working test"

This reverts commit ae415de566d06b4e055187ea94e790db88589494.

As per bugzilla bug 1112657, it should be possible to use a wide variety of
characters in a role's name. For example, the following should be valid role
names:

* foo@bar.com
* チーズ

This issue was fixed, but it appears that a regression has occurred. Bugzilla
bug 1112657 should be re-opened.
Merge pull request #1252 from Ichimonji10/role-names

Revert "Remove 'skip' decorator from working test"
Change which BZ bug states cause a test to skip

Make the `skip_if_bug_open` decorator skip a test if it points to a bugzilla bug
in any of the following states:

* NEW
* ASSIGNED
* POST
* MODIFIED

Formerly, only the 'NEW' and 'ASSIGNED' bugzilla bug states caused
`skip_if_bug_open` to skip a test.