Merge from origin/emacs-27

e7a3ed8a6d Fix tab-bar-tab-name-ellipsis initialization
4737d0af75 Fix Elisp manual entry for format-spec
0195809bb6 Fix rare assertion violations in 'etags'
cddb0079ff ; * lisp/format-spec.el (format-spec): Fix typo.

diff --cc doc/lispref/text.texi
Simple merge

diff --cc lib-src/etags.c
Simple merge

diff --cc lisp/tab-bar.el
Simple merge