Question: How to factor out sqrt(2)

I am looking for a command that extracts sqrt(2) from

sqrt(4 + (-2*x - 2)*y)

The expression above is a subexpression of a larger expression generated by Maple (an integral).
In this situation manual workarounds are impractical and errorprone.

Ideally Maple should return

sqrt(2)*sqrt(2 - (x + 1)*y)

I tried simplify, factor, collect and so on...

In case that there is nothing (which I doubt):
Why is Maple not having simple commands that do extraction (and absortion/inclusion) of factors?

(extract and absorb are names not used so far that would be easy to remember.)  

Update - example of an expression:

expr := Int(sqrt(-2*alpha^2*x - 2*alpha^2 + 4)/(sqrt(-alpha^2 + 1)*(-alpha^2*x - alpha^2 + 2)), alpha = 0 .. z) = EllipticF(z, sqrt(2*x + 2)/2)