migration 1 was previously applied but has been modified

Display: migration 1 was previously applied but has been modified
Debug:   VersionMismatch(1)

const V1: &str = "create table pit2.mm_users (id int8 primary key);\n";
const V1_EDITED: &str = "create table pit2.mm_users (id int8 primary key, email text);\n";
const V2: &str = "alter table pit2.mm_users add column name text;\n";
const V3: &str = "alter table pit2.mm_users add column email text;\n";

write("1_users.sql", V1)?;
write("2_users_name.sql", V2)?;
let a = pool(&opts).await?;
Migrator::new(dir().as_path()).await?.run(&a).await?;

write("1_users.sql", V1_EDITED)?;
write("3_users_email.sql", V3)?;
let err = Migrator::new(dir().as_path()).await?.run(&a).await.unwrap_err();
// 然后：查池 A 那条连接持有的 advisory 锁；
// 把 1_users.sql 改回 V1，用另一个池 B 跑迁移，等 3 秒；关掉池 A，池 B 再跑

第一次部署: 已应用 [(1, "users"), (2, "users name")]
--- 改了 1_users.sql，又加了 3_users_email.sql ---
Display: migration 1 was previously applied but has been modified
Debug:   VersionMismatch(1)
已应用 [(1, "users"), (2, "users name")]
mm_users 的列 ["id", "name"]
出错后池 A 的连接 (pid 1031) 持有的 advisory 锁: [(1031, "ExclusiveLock", true)]
--- 另一个实例（池 B）用改回来的目录跑迁移，等 3 秒 ---
池 B: Err(Elapsed(()))
--- 关掉池 A，池 B 再跑 ---
池 B: Ok(Ok(()))
已应用 [(1, "users"), (2, "users name"), (3, "users email")]
mm_users 的列 ["id", "name", "email"]

            match applied_migrations.get(&migration.version) {
                Some(applied_migration) => {
                    if migration.checksum != applied_migration.checksum {
                        return Err(MigrateError::VersionMismatch(migration.version));
                    }
                }
                None => {
                    if skip {
                        conn.skip(&self.table_name, migration).await?;
                    } else {
                        conn.apply(&self.table_name, migration).await?;
                    }
                }
            }
        }

        // unlock the migrator to allow other migrators to run
        // but do nothing as we already migrated
        if self.locking {
            conn.unlock().await?;
        }

let m = Migrator::new(dir().as_path()).await?;
let new_sum = m.iter().find(|m| m.version == 1).map(|m| m.checksum.to_vec()).unwrap_or_default();
sqlx::query("update pit2._sqlx_migrations set checksum = $1 where version = 1")
  .bind(&new_sum)
  .execute(&mut observer)
  .await?;

--- 最后手段: 把库里的 checksum 改成新文件的 ---
update 1 行
run = Ok(())
mm_users 的列 ["id", "name", "email"]
--- 同一个目录，在一个新库上从头跑 ---
run = Err("while executing migration 3: error returned from database: column \"email\" of relation \"mm_users\" already exists at line 7347")
已应用 [(1, "users"), (2, "users name")]

--- 一个 -- no-transaction 文件里两条 CONCURRENTLY ---
run = Err: while executing migration 1: error returned from database: CREATE INDEX CONCURRENTLY cannot run inside a transaction block at line 3497
索引 []，已应用 []
--- 拆成两个文件，各带 -- no-transaction ---
run = Ok
索引 ["multi_a", "multi_b"]，已应用 [1, 2]

URL='postgres://lab:lab@192.168.64.106/lab?options=-c%20search_path%3Dpit2'
sqlx migrate info --source mm --database-url "$URL"; echo "info exit=$?"
sqlx migrate run --source mm --database-url "$URL"; echo "run exit=$?"

1/installed (different checksum) users
applied migration had checksum 715fc1d96dec702690da76fe9642b7983cd1f4c5cb02d07def6386bf49b263206922263a8f9d1aa06d1f9dcb22cfb473
local migration has checksum 88eda3638e8eb1f1d768a191fc219346861c02fec8a39769ab3b39b8deb8f21290604b91a2f7d5e134667d514ea92be5
2/installed users name
3/installed users email
info exit=0
error: migration 1 was previously applied but has been modified
run exit=1