Suggested by Pip Cet.

* test/lisp/vc/ediff-mult-tests.el (ediff-test-bug3348): Clean up.

* test/lisp/vc/vc-git-tests.el (vc-git-test-branch-remotes):
The 'unset' subcommand to 'git config' was introduced in git 2.46; use
the '--unset' option instead.

* lisp/vc/vc-git.el (vc-git--branch-remotes): New function.
(vc-git-trunk-or-topic-p): Use it.
* test/lisp/vc/vc-git-tests.el (vc-git-test-branch-remotes): New
test.

* lisp/vc/vc-git.el (vc-git--current-branch): Rename to ...
(vc-git-working-branch): ... this.  All uses changed.
(vc-git-trunk-or-topic-p, vc-git-topic-outgoing-base):
* lisp/vc/vc-hg.el (vc-hg--working-branch, vc-hg-working-branch)
(vc-hg-trunk-or-topic-p, vc-hg-topic-outgoing-base):
* lisp/vc/vc-hooks.el (vc--safe-branch-regexps-p):
* lisp/vc/vc.el (vc-default-working-branch)
(vc-default-trunk-or-topic-p, vc--match-branch-name-regexps)
(vc--outgoing-base, vc--outgoing-base-mergebase)
(vc--maybe-read-outgoing-base): New functions.
(vc-diff-outgoing-base): Call vc--outgoing-base-mergebase.
(vc-root-diff-outgoing-base, vc-diff-outgoing-base): Use
vc--maybe-read-outgoing-base in interactive specification.
(working-branch, trunk-or-topic-p, topic-outgoing-base): New
specifications for backend functions.
(vc-trunk-branch-regexps, vc-topic-branch-regexps): New
variables.
* .dir-locals.el: Commented entries for the new variables.
* test/lisp/vc/vc-tests/vc-test-misc.el
(vc-test-match-branch-name-regexps): New test.
* doc/emacs/vc1-xtra.texi (Outstanding Changes): Document the
new functionality.

Some of the fixes are to continue to use American
rather than British spelling.
* doc/misc/modus-themes.org (my-modus-themes-engraved-faces):
Fix misspelled ‘:foreground’s.
* etc/themes/modus-themes.el (modus-themes-faces):
Fix misspelled ‘modus-themes-bold’.
* lisp/emacs-lisp/rx.el (rx--normalize-char-pattern):
Rename from rx--normalise-char-pattern.
(rx--optimize-or-args):	Rename from rx--optimise-or-args.
* lisp/frame.el (frame--special-parameters):
Fix misspelled "right-divider-width".
* lisp/net/tramp.el (tramp-fingerprint-prompt-regexp):
Use American spelling “centered”, to match current libfprintf.
* lisp/org/org-fold-core.el (org-fold-core--optimize-for-huge-buffers):
Rename from org-fold-core--optimise-for-huge-buffers.
(org-fold-core-update-optimization):
Rename from org-fold-core-update-optimisation,
leaving an alias behind.
(org-fold-core-remove-optimization):
Rename from org-fold-core-remove-optimisation,
leaving an alias behind.
* lisp/org/org.el (org-advertized-archive-subtree):
This alias is now obsolete.
* lisp/play/zone.el (zone-ignored-buffers):
Fix misspelling of ‘zone--buffer-encrypted-p’.
* lisp/progmodes/csharp-mode.el (csharp-ts-mode-faces):
Fix misspelling of ‘csharp’ group.
* lisp/vc/vc.el (vc-clonable-backends-custom-type):
Rename from vc-cloneable-backends-custom-type,
leaving an alias behind.
* test/lisp/emacs-lisp/bytecomp-tests.el:
(bytecomp-tests--warn-arity-non-compiled-callee):
Rename from bytecomp-tests--warn-arity-noncompiled-callee.
(bytecomp-test-defface-spec): Reword a deliberate misspelling
of “default” that is so common I don’t want it to pollute the
spelling dictionary.
* test/lisp/emacs-lisp/package-vc-tests.el:
(package-vc-tests-preserve-artifacts):
Rename from package-vc-tests-preserve-artifacts.
* test/lisp/eshell/em-prompt-tests.el:
(em-prompt-test/forward-backward-paragraph-1):
Reword a deliberate misspelling of “goodbye” that is so common I
don’t want it to pollute the spelling dictionary.

* test/lisp/vc/vc-git-tests.el (vc-git-test--with-repo): Use
example.com, domain following RFC 2606.
* test/lisp/vc/vc-tests/vc-tests.el
(vc-test--with-author-identity): Use example.com, domain
following RFC 2606.