Replicate pending selections separately from other selections

This fixes a panic that would occur when a leader created
a pending selection that overlapped another selection,
because the follower would attempt to treat that pending
selection as non-pending, which would violate the invariant
that selections are sorted and disjoint.

crates/rpc/src/rpc.rs

@@ -6,4 +6,4 @@ pub use conn::Connection;
 pub use peer::*;
 mod macros;
 
-pub const PROTOCOL_VERSION: u32 = 43;
+pub const PROTOCOL_VERSION: u32 = 44;