Preserve query string when redirecting POSTs to GETs

[edwardhorsford]

When the kit redirects POSTs to GETs it doesn't preserve any query string in the url. This updates to preserve that.

This means if a query string is included in the form action, when the user is redirected to the resulting GET url, that query string is as it was.

This is useful when:

• You’re using the query string to set flash messages or return paths
• You want to rely on explicitly what’s in the query string for a specific page, rather than saved data.

I added support for this in our service in September last year and it's worked well - you can now use query strings seamlessly and they're preserved regardless of whether you're doing a GET or a POST.

[joelanman]

looks good thanks, just waiting on a review with the rest of the team

[domoscargin]

This looks good to me, thanks @edwardhorsford.

Do you want to add a feature changelog entry? Happy to do it myself.

[edwardhorsford]

@domoscargin added a changelog entry. Hope the formatting is ok. Do you allow commits to be squashed on merge, or does that need to happen beforehand?

[domoscargin]

@domoscargin added a changelog entry. Hope the formatting is ok. Do you allow commits to be squashed on merge, or does that need to happen beforehand?

We generally squash beforehand.

[edwardhorsford]

@domoscargin well I borked that. Rather than squashing, I seem to have brought in all the intermediary commits on the kit. Can you help?

[domoscargin]

@edwardhorsford Should be sorted.

We're just going to write some documentation for this.

[edwardhorsford]

Thanks both!