Fix program account rent exemption (#14176)

programs/bpf/rust/upgradeable/src/lib.rs

@@ -8,9 +8,10 @@ use solana_program::{
 entrypoint!(process_instruction);
 fn process_instruction(
     _program_id: &Pubkey,
-    _accounts: &[AccountInfo],
+    accounts: &[AccountInfo],
     _instruction_data: &[u8],
 ) -> ProgramResult {
     msg!("Upgradeable program");
+    assert_eq!(accounts.len(), 2);
     Err(42.into())
 }