These were all tested with https and confirmed working.

(ruby-mode-map, ruby-mode-menu): Don't use ruby-for/backward-sexp any more.
(ruby-mode-variables): Always setup SMIE navigation.
Still obey `ruby-use-smie` for indentation.
(ruby-forward-sexp, ruby-backward-sexp): Mark as obsolete.

* lisp/progmodes/ruby-mode.el (ruby-parse-partial):
Don't call ruby-deep-indent-paren-p (bug#42841).

Make regexps smaller and faster by removing terms that are superfluous
by virtue of standing next to another term that matches more.  See
https://lists.gnu.org/archive/html/emacs-devel/2020-01/msg00949.html
for details.

* lisp/bs.el (bs--make-header-match-string):
* lisp/gnus/deuglify.el (gnus-outlook-repair-attribution-block):
* lisp/gnus/message.el (message-subject-trailing-was-ask-regexp)
(message-subject-trailing-was-regexp):
* lisp/informat.el (Info-validate):
* lisp/net/browse-url.el (browse-url-button-regexp):
* lisp/net/rcirc.el (rcirc-url-regexp):
* lisp/org/ob-core.el (org-babel-remove-result):
* lisp/org/ob-fortran.el (org-babel-fortran-ensure-main-wrap):
* lisp/org/org-capture.el (org-capture-set-target-location):
* lisp/org/org-table.el (org-table-expand-lhs-ranges):
* lisp/org/org.el (org-maybe-keyword-time-regexp, org-ts-regexp)
(org-ts-regexp-inactive, org-ts-regexp-both):
* lisp/play/gametree.el (gametree-hack-file-layout):
* lisp/progmodes/cc-mode.el (c-Java-defun-prompt-regexp):
* lisp/progmodes/idlw-shell.el (idlwave-shell-halting-error):
* lisp/progmodes/ruby-mode.el (ruby-mode-set-encoding):
* lisp/progmodes/verilog-mode.el (verilog-error-font-lock-keywords)
(verilog-verilint-off, verilog-case-indent-level)
(verilog-within-translate-off, verilog-start-translate-off)
(verilog-back-to-start-translate-off, verilog-end-translate-off)
(verilog-expand-dirnames):
* lisp/term.el (term-control-seq-regexp):
* lisp/textmodes/reftex-vars.el (featurep):
* lisp/url/url-gw.el (url-open-telnet):
* lisp/vc/ediff-ptch.el (ediff-context-diff-label-regexp):
* lisp/vc/pcvs-parse.el (cvs-parse-status):
* test/src/regex-emacs-tests.el (regex-tests-PCRE):
Remove subsumed repetitions.
* lisp/progmodes/sh-script.el (sh-syntax-propertize-function):
Simplify repetition of a repetition.

Run "TZ=UTC0 admin/update-copyright $(git ls-files)".

* lisp/allout-widgets.el (allout-decorate-item-icon):
* lisp/emacs-lisp/chart.el (chart-goto-xy):
* lisp/forms.el (forms--make-format)
(forms--make-format-elt-using-text-properties):
* lisp/htmlfontify.el (hfy-unmark-trailing-whitespace):
* lisp/net/newst-plainview.el (newsticker-hide-entry)
(newsticker-show-entry):
* lisp/nxml/nxml-mode.el (nxml-cleanup):
* lisp/obsolete/longlines.el (longlines-unshow-hard-newlines)
(longlines-encode-region):
* lisp/org/ob-exp.el (org-babel-exp-process-buffer):
* lisp/org/org-agenda.el (org-agenda-show-new-time):
* lisp/progmodes/cc-defs.el
(c-clear-char-property-with-value-function)
(c-clear-char-property-with-value-on-char-function):
* lisp/progmodes/ebrowse.el (ebrowse--hide):
* lisp/progmodes/gdb-mi.el (gdb-send):
* lisp/progmodes/idlw-shell.el
(idlwave-retrieve-expression-from-level):
* lisp/progmodes/make-mode.el (makefile-fill-paragraph):
* lisp/progmodes/prog-mode.el (prettify-symbols--post-command-hook):
* lisp/progmodes/ruby-mode.el (ruby-syntax-propertize):
* lisp/tmm.el (tmm-remove-inactive-mouse-face):
Always pass an explicit plist to remove-text-properties.

* lisp/dired.el (dired--unhide):
* lisp/facemenu.el (facemenu-add-face):
* lisp/htmlfontify.el (hfy-fontify-buffer):
* lisp/iimage.el (iimage-mode-buffer):
* lisp/image-file.el (image-file-yank-handler):
* lisp/progmodes/prog-mode.el (prettify-symbols--compose-symbol):
* lisp/textmodes/tex-mode.el (latex-env-before-change):
* test/src/undo-tests.el (undo-test0):
Use remove-list-of-text-properties in place of
remove-text-properties where appropriate.

* lisp/progmodes/ruby-mode.el (ruby-brace-to-do-end):
Strip trailing whitespaces at the end of converted do block
(bug#36756).

https://bugs.ruby-lang.org/issues/16014
https://github.com/syl20bnr/spacemacs/issues/12548

* lisp/progmodes/ruby-mode.el (ruby-find-library-file):
Omit the misplaced and unnecessary shyness qualifier.
Suggested by Mattias Engdegård <mattiase@acm.org>.

* lisp/progmodes/ruby-mode.el (ruby-find-library-file):
New command.
(ruby-mode-map): Add binding for it.