XSRF token mismatch error when using the "create" form to update a link

[offbyone]

If I use the create form on /go/ to update a link that already exists:

Rather than an updated link (my preferred outcome), an intermediate form indicating a collision with an offer to overwrite (probably the right outcome) or an error indicating that the link is duplicated (least ideal), what I instead get is a plain text HTTP response "Invalid XSRF token"

This is sort of related to #130 -- I think it's the same issue, and the users haven't recognized that they are creating duplicates -- and #156, which is about "renaming" a link.

[zofrex]

Easily reproduced locally in dev mode. Looking into it!

[willnorris]

oh, I just realized that xsrf was just the current error, but the request was more about the behavior when creating duplicate links? If Patrick's PR (which removes xsrf tokens) didn't actually fix this, feel free to reopen.