Copy field code not working when session id is in the cp url

[robinsowell]

EE 7.5.3

On the field manager and in the entry edit, if you're using sessions in the cp, the copy field doesn't work.

I tried it- it triggers a url like https://75gen:8890/admin.php?/cp/design/copy/fields&S=1053ee30af84cfc809af3cdaea3f78ce/5 which 404's.

URL should be https://75gen:8890/admin.php?/cp/design/copy/fields/5&S=1053ee30af84cfc809af3cdaea3f78ce/ - basically we just need to switch it up and it should be fine.