replace all does not account for line change

[SilenZcience]

The search and replace functionality does not account for line change when replacing all occurences.

Example:
Write a simple file with the following content:

A_A_

and have the cursor on the last position.
When replacing every A with XXX (or anything of length 3 or greater) the following change will be made:

XXX_A_

The expected bahavior would be to have the following result:

XXX_XXX_

[asottile]

should be pretty easy to fix if you'd like to send a patch