Remove confusing “You are already signed in.” flash message (#13547)
Remove confusing “You are already signed in.” flash message (#13547)

When attempting to access the log-in page while already logged in,
Devise's `require_no_authentication` kicks in and sets a flash
message “You are already signed in.”

In almost all cases, this also causes a redirect to /web, which
does not display or clear flash messages, thus leaving the message
to a potentially much later date, like for instance, accessing
/preferences several minutes after being redirected to /web.
Ryanaka/mastodon,Nyoho/mastodon,h3zjp/mastodon,rainyday/mastodon,imas/mastodon,Kirishima21/mastodon,abcang/mastodon,im-in-space/mastodon,rainyday/mastodon,koba-lab/mastodon,glitch-soc/mastodon,ykzts/mastodon,tootsuite/mastodon,cobodo/mastodon,gol-cha/mastodon,imas/mastodon,musashino205/mastodon,primenumber/mastodon,abcang/mastodon,yukimochi/mastodon,yi0713/mastodon,im-in-space/mastodon,maa123/mastodon,theoria24/mastodon,Nyoho/mastodon,glitch-soc/mastodon,lindwurm/mastodon,MitarashiDango/mastodon,masto-donte-com-br/mastodon,h3zjp/mastodon,MitarashiDango/mastodon,h3zjp/mastodon,koba-lab/mastodon,yi0713/mastodon,theoria24/mastodon,masto-donte-com-br/mastodon,abcang/mastodon,tri-star/mastodon,im-in-space/mastodon,pinfort/mastodon,Nyoho/mastodon,danhunsaker/mastodon,koba-lab/mastodon,gol-cha/mastodon,Ryanaka/mastodon,Kirishima21/mastodon,koba-lab/mastodon,maa123/mastodon,Nyoho/mastodon,Kirishima21/mastodon,tootsuite/mastodon,lindwurm/mastodon,musashino205/mastodon,primenumber/mastodon,danhunsaker/mastodon,MitarashiDango/mastodon,abcang/mastodon,im-in-space/mastodon,rainyday/mastodon,theoria24/mastodon,ykzts/mastodon,pinfort/mastodon,tri-star/mastodon,ykzts/mastodon,h3zjp/mastodon,tootcafe/mastodon,maa123/mastodon,tootcafe/mastodon,masto-donte-com-br/mastodon,ikuradon/mastodon,pinfort/mastodon,danhunsaker/mastodon,theoria24/mastodon,rainyday/mastodon,yukimochi/mastodon,tri-star/mastodon,Ryanaka/mastodon,maa123/mastodon,ikuradon/mastodon,pinfort/mastodon,tootsuite/mastodon,lynlynlynx/mastodon,yukimochi/mastodon,ikuradon/mastodon,glitch-soc/mastodon,MitarashiDango/mastodon,Kirishima21/mastodon,lynlynlynx/mastodon,primenumber/mastodon,lindwurm/mastodon,danhunsaker/mastodon,yi0713/mastodon,tootcafe/mastodon,imas/mastodon,cobodo/mastodon,cobodo/mastodon,Ryanaka/mastodon,imas/mastodon,gol-cha/mastodon,cobodo/mastodon,tootcafe/mastodon,musashino205/mastodon,musashino205/mastodon,yi0713/mastodon,ikuradon/mastodon,gol-cha/mastodon,tootsuite/mastodon,lindwurm/mastodon,lynlynlynx/mastodon,lynlynlynx/mastodon,yukimochi/mastodon,ykzts/mastodon,tri-star/mastodon,primenumber/mastodon,masto-donte-com-br/mastodon,glitch-soc/mastodon