Updating only updatedAt on a model does not cause an update, even with silent: true

What are you doing?

person = Person.create({ name: 'Original Name'})
await Person.update({ updatedAt: new Date('02-26-1991')}, {where: { id: person.id }, silent: true})
// [ 0 ]

await person.reload()
await person.updatedAt
// 2019-04-12T20:13:52.923Z

await Person.update({ updatedAt: new Date('02-26-1991'), name: 'A New Name'}, {where: { id: person.id }, silent: true})
Executing (default): UPDATE "Person" SET "updatedAt"=$1,"name"=$2 WHERE "id" = $3
// [ 1 ]

await person.reload()
person.updatedAt
// 1991-02-26T05:00:00.000Z

To Reproduce Steps to reproduce the behavior:

1. Create a model Person and an instance person
2. Use Person.update to update only the updatedAt field on person
3. Reload person to see that updatedAt has not been updated

What do you expect to happen?

I expected updatedAt to be updated,

What is actually happening?

updatedAt was not updated

Environment

Dialect:

• mysql
• postgres
• sqlite
• mssql
• any Dialect library version: XXX Database version: PostgreSQL 9.6 Sequelize version: 5.10.0 Node Version: 10.15.3 OS: Ubuntu 18.04.1 on Windows 10 Tested with latest release:
• No
• Yes, specify that version: 5.10.0

[jamelling]

I only use it while doing tests for some filtering of data by updatedAt times.

I think it was introduced as a side effect of https://github.com/sequelize/sequelize/pull/10248, which was to prevent updating the updatedAt time when Model.update({ }, { where: { id: someId } }) was called, as this used to behave like I expect it to.

[papb]

Duplicate of #3759