A @font-face declaration may contain a fragment that looks like a relative path,
e.g. @font-face { src: url('../fonts/font.svg#../path/like/fragment'); }
In this case, an incorrect path was passed to the storage backend, which raised
an error that caused collectstatic to crash.
This requires that each test never alters files in static directories
collected by other tests. The alternative is to add a temporary
directory to STATICFILES_DIRS or a new app to INSTALLED_APPS.