Array of tuple default initializer assignability issue

[tinganho]

TypeScript Version: 2.2.1 / nightly (2.2.0-dev.201xxxxx)

Code

let a: [string, 'asc' | 'desc'][];
a = [['some', 'asc']]; // No error

class A {
    a: [string, 'asc' | 'desc'][];
}

class B extends A {
    a = [['some', 'asc']]; // Error string[][] is not assignable to [string, 'asc' | 'desc'][]
}

Expected behavior:
The default initialised member a in class B should not error.

Actual behavior:
The default initialised member a errors.

[RyanCavanaugh]

Duplicate #10570