[test/web] fix invisibly bogus test (prepares #2755994) The test was wrong but that was cancelled out by a cache effect and fuzzy naming. Wiping the entity caches restores sanity: the choices list are the same before and after the SET. Also field.choices uses entity.unrelated but always returns related + unrelated elements. Hence `choice` replaces `unrelated` where it makes sense. AssertIn is used in place of AssertTrue.

usr/lib/python2.4/site-packages/cubicweb/
etc/init.d
etc/cubicweb.d
etc/bash_completion.d
usr/bin
usr/share/doc/cubicweb-ctl
var/log/cubicweb
var/lib/cubicweb/backup
var/lib/cubicweb/instances