Subject: bug#55166: 28.1; tar-mode doesn't re-compress when saving remote files

From: Dan McCarthy <[email-masked]>
Date: Thu, 28 Apr 2022 11:43:36 -0400

On a remote machine:

dan@solstice:/tmp$ touch a b c
dan@solstice:/tmp$ tar cf test.tar a b c
dan@solstice:/tmp$ bzip2 -z test.tar
dan@solstice:/tmp$ file test.tar.bz2
test.tar.bz2: bzip2 compressed data, block size = 900k

If you visit that remote file and save it, the result will have the .bz2
extension but won't actually be compressed:

dan@solstice:/tmp$ file test.tar.bz2
test.tar.bz2: POSIX tar archive (GNU)

This doesn't happen with compressed remote files which aren't tar archives.

In GNU Emacs 28.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.31,
cairo version 1.16.0)
 of 2022-04-12 built on october.example.org
Windowing system distributor 'The X.Org Foundation', version 11.0.12014000
System Description: Slackware 15.0 x86_64

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND
THREADS TIFF TOOLKIT_SCROLL_BARS X11 XDBE XIM XPM GTK3 ZLIB

Important settings:
  value of $LC_COLLATE: C
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  shell-dirtrack-mode: t
  hexl-follow-ascii: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tab-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
~/.emacs.d/lisp/android-mode hides
/home/blakestone/.emacs.d/elpa/android-mode-20190903.811/android-mode
~/.emacs.d/lisp/connection hides
/home/blakestone/.emacs.d/elpa/connection-20191111.446/connection
~/.emacs.d/lisp/link hides
/home/blakestone/.emacs.d/elpa/link-20191111.446/link
/home/blakestone/.emacs.d/elpa/transient-20220425.1314/transient hides
/usr/local/share/emacs/28.1/lisp/transient
/home/blakestone/.emacs.d/elpa/dictionary-20201001.1727/dictionary hides
/usr/local/share/emacs/28.1/lisp/net/dictionary
~/.emacs.d/lisp/greek hides /usr/local/share/emacs/28.1/lisp/language/greek
~/.emacs.d/lisp/longlines hides
/usr/local/share/emacs/28.1/lisp/obsolete/longlines

Features:
(shadow sort mail-extr ffap emacsbug message rmc puny rfc822 mml mml-sec
epa epg rfc6068 epg-config gnus-util rmail rmail-loaddefs mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils vc-hg
vc-git diff-mode easy-mmode vc-bzr vc-dispatcher tar-mode arc-mode
archive-mode jka-compr pcmpl-unix pcmpl-gnu with-editor compat dired-aux
dired dired-loaddefs tramp-cache tramp-sh executable misearch
multi-isearch edmacro kmacro cua-base cus-load acme-search quack
thingatpt compile text-property-search cmuscheme scheme advice tramp
tramp-loaddefs trampver tramp-integration files-x tramp-compat shell
pcomplete comint ring parse-time iso8601 time-date ls-lisp format-spec
ansi-color c-xref rx session vanc-init bindat vanc-mode hexl ecf-mode
derived cl-extra help-mode dcm-general server cl info package browse-url
url url-proxy url-privacy url-expand url-methods url-history url-cookie
url-domsuf url-util mailcap url-handlers url-parse auth-source cl-seq
eieio eieio-core cl-macs eieio-loaddefs password-cache json subr-x map
url-vars seq byte-opt gv bytecomp byte-compile cconv cl-loaddefs cl-lib
iso-transl tooltip eldoc paren electric uniquify ediff-hook vc-hooks
lisp-float-type elisp-mode mwheel term/x-win x-win term/common-win x-dnd
tool-bar dnd fontset image regexp-opt fringe tabulated-list replace
newcomment text-mode lisp-mode prog-mode register page tab-bar menu-bar
rfn-eshadow isearch easymenu timer select scroll-bar mouse jit-lock
font-lock syntax font-core term/tty-colors frame minibuffer cl-generic
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese composite emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help simple abbrev obarray
cl-preloaded nadvice button loaddefs faces cus-face macroexp files
window text-properties overlay sha1 md5 base64 format env code-pages
mule custom widget hashtable-print-readable backquote threads dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 166897 25031)
 (symbols 48 15286 4)
 (strings 32 52764 4059)
 (string-bytes 1 1727857)
 (vectors 16 31379)
 (vector-slots 8 983720 94988)
 (floats 8 84 70)
 (intervals 56 9204 1194)
 (buffers 992 22))