unable to change keybase.io website login passphrase

I can login to the site just fine, but when I go to `/_/user/account` and enter the exact same passphrase I used to login to the "current passphrase" box and a new passphrase in the two "new passphrase" boxes, it processes and finally ends with `Error In Update: Bad current passphrase` and my passphrase is not changed — I can still logout and login on the website using the old pass phrase.

Start by reproducing the passphrase change flow at /_/user/account with the same current passphrase used to log in, and inspect the account-update request and its error response. Done means a valid current passphrase is accepted, the new passphrase is stored, and the new passphrase works for a subsequent website login.

Written by the indexing model from the issue text.