track rust version when using local monorepo (#4064)

Author: 2501babe

patch.crates-io.sh

@@ -24,6 +24,8 @@ solana_dir=$(cd "$solana_dir" && pwd)
 cd "$(dirname "$0")"
 
 source "$solana_dir"/scripts/read-cargo-variable.sh
+cp "$solana_dir"/rust-toolchain.toml .
+
 # get version from Cargo.toml first. if it is empty, get it from other places.
 solana_ver="$(readCargoVariable version "$solana_dir"/Cargo.toml)"
 solana_ver=${solana_ver:-$(readCargoVariable version "$solana_dir"/sdk/Cargo.toml)}