Postgres enum is recreated in every new generated migration

[Nazar910]

Issue type:

[ ] question
[x] bug report
[ ] feature request
[ ] documentation issue

Database system/driver:

[ ] cordova
[ ] mongodb
[ ] mssql
[ ] mysql / mariadb
[ ] oracle
[x] postgres
[ ] cockroachdb
[ ] sqlite
[ ] sqljs
[ ] react-native
[ ] expo

TypeORM version:

[ ] latest
[ ] @next
[x] 0.2.24 (or put your version here)

Steps to reproduce or a small repository showing the problem:
Hi, I have entity that uses enum as column type like this:

import {
    Entity, Column, PrimaryGeneratedColumn, Unique,
} from 'typeorm';

export enum CreationMechanism {
    SOURCE_A = 'SOURCE_A',
    SOURCE_B = 'SOURCE_B',
    SOURCE_C = 'SOURCE_C',
    SOURCE_D = 'SOURCE_D'
}

@Entity({ name: 'some_entity' })
@Unique([
    'field1',
    'field2',
])
export class SomeEntity {
    @PrimaryGeneratedColumn()
    id: number;

    @Column()
    field1: string;

    @Column()
    field2: string;

    @Column({
        type     : 'enum',
        enumName : 'creation_mechanism_enum',
        enum     : CreationMechanism,
    })
    creationMechanism: CreationMechanism;

    @Column({ nullable: false, default: () => 'now()' })
    createdAt: Date;
}

Every time I want to generate new migration it always contains recreating of the previously defined enum. For example, I generated migration which contained recreating of an enum, and again executed migration generation, and now I have empty migration with the recreation of enum like this:

...
    public async up(queryRunner: QueryRunner): Promise<void> {
        await queryRunner.query(`ALTER TYPE "public"."creation_mechanism_enum" RENAME TO "creation_mechanism_enum_old"`, undefined);
        await queryRunner.query(`CREATE TYPE "creation_mechanism_enum" AS ENUM('SOURCE_A', 'SOURCE_B', 'SOURCE_C', 'SOURCE_D')`, undefined);
        await queryRunner.query(`ALTER TABLE "some_entity" ALTER COLUMN "creationMechanism" TYPE "creation_mechanism_enum" USING "creationMechanism"::"text"::"creation_mechanism_enum"`, undefined);
        await queryRunner.query(`DROP TYPE "creation_mechanism_enum_old"`, undefined);
    }
...

Please give me a hint if I'm doing something wrong. Thanks in advance.

[Nazar910]

Postgres version 11.8

[4PTEM]

Im still facing this issue in version 0.3.20

[gigigimay]

Confirmed, still facing this issue in version 0.3.20