tgz extension and dired-do-compress

[Uwe Brauer]

Hi   The setting of the variable    dired-filetype-compress-regexp 
is a variable defined in ‘dired-filetype-face.el’.  Its value is 
("7Z" "7z" "apk" "bz2" "bzip2" "cab" "deb" "ear" "gpg" "gz" "gzip" 
"img" "iso" "jar" "lzma" "pkg" "RAR" "rar" "rpm" "tar" "taz" 
"tbz2" "tgz" "txz" "war" "wim" "XAR" "xar" "XZ" "xz" "Z" "z" "ZIP" 
"zip") 

So tgz is included. 


However whenever I try to run dired-do-compress on a tgz archive it is 
not uncompressed to a tar archive. What do I miss? 

It seems that this feature is missing.

Uwe Brauer