Merge from origin/emacs-27

bed04c502c Use correct registry name for windows-1251 charset
1aa1529301 ERC: Update maintainer address

diff --cc lisp/erc/erc-backend.el
Simple merge

diff --cc lisp/erc/erc-ezbounce.el
Simple merge

diff --cc lisp/erc/erc-speedbar.el
Simple merge