The test case is:
"mentions message when a single message was pinned, with multiple previously pinned messages"
However, the test case was also unpinning messages. That is now fixed.
Signed-off-by: Paulo Pinto <paulo.pinto@automattic.com>
So that there's one top level `describe('TextForEvent')`, followed by a nested
`describe('textForPinnedEvent')`, containting all the `it()`s.
Signed-off-by: Paulo Pinto <paulo.pinto@automattic.com>