The behavior of this acts as if it's renaming the original "pk" variable to something else. Without this, "pk" still persists as well as the new reference.
Not sure if the original behavior is intended or not, just an observation made. Feel free to reject. :)
If AJAX_PK_ATTR_NAME is set, we want to remove the original reference…
… to "pk" since this is acting as a rename of the same variable
Eh, should catch some more edge cases just incase there isn't a PK at…
… all. Say it was excluded or something.
I should be deleting the pk field from the data. Going to reject this as it's not quite in line with the original requirement. I'll fix it in a separate commit.