sync: revert Clone impl for broadcast::Receiver (#3020)

The `Receiver` handle maintains a position in the broadcast channel for
itself. Cloning implies copying the state of the value. Intuitively,
cloning a `broadcast::Receiver` would return a new receiver with an
identical position. However, the current implementation returns a new
`Receiver` positioned at the tail of the channel.

This behavior subtlety is why `new_subscriber()` is used to create
`Receiver` handles. An alternate API should consider the position issue.

Refs: #2933

0 files changed, 0 insertions, 0 deletions