fix cond in scopes

[black-06]

• Do only one thing
• Non breaking API changes
• Tested

What did this pull request do?

fix conditions in Scope #6148

User Case Description

DB.Table("test").Scopes(
	func(d *gorm.DB) *gorm.DB {
		return d.Where("a = 1")
	},
	func(d *gorm.DB) *gorm.DB {
		return d.Where(d.Or("b = 2").Or("c = 3"))
	},
).Rows()

It should be:

SELECT * FROM `test` WHERE a = 1 AND (b = 2 OR c = 3)

But now it is:

SELECT * FROM `test` WHERE a = 1 OR b = 2 OR c = 3 AND (a = 1 OR b = 2 OR c = 3)

[jinzhu]

in a scope condition, it might have other scope conditions, so we are writing the code like this:

for len(db.Statement.scopes) > 0 {
	db = db.executeScopes(false)
		scopes := db.Statement.scopes
		db.Statement.scopes = nil
		for _, scope := range scopes {
			db = scope(db)
		}
	}

Seems like the change will break it.

[black-06]

Sorry, it's my fault.