Previously, when one logged into their Yahoo email account, they'd be presented with a page
showing the Inbox, pending messages, etc.
Now, one is presented with a screen demanding a mobile phone number. It's possible to
get past that screen without supplying one (thanks, Yahoo, for forgetting that there are many
poor people who can't afford mobile phones and many deaf people who don't have one),
but it appears that this screen is presented every time one logs in. This breaks fetchyahoo.
Note: this may be region-specific; I'm in the US and I suppose it's possible that it's not
being done with logins originate from other counries and/or are for accounts whose
addresses are in other countries.
Repeat-by: run fetchyahoo using any account that hasn't supplied a mobile number.