pin update $cid $cid yields no error when $cid is not pinned

#### Version information:
go-ipfs version: 0.7.0-ea77213e3
Repo version: 10
System version: amd64/linux
Golang version: go1.15.2

#### Description:
`ipfs pin update $cidA $cidA`
gives no error and even states the update was successful even though $cidA is not pinned.
As opposed to
`ipfs pin update $cidA $cidB`
where you get the error `'from' cid was not recursively pinned already`

Relevant issue #6648