bug#58367: `package-install-file' rejects some .tar files (tentative patch)

[Richard Hopkins]

I've found another difference regarding `package-install-file' and a
package with subdirectories that I can reproduce with the previously
attached files.  This is the difference between installing a directory
or installing a .tar file.  For example

M-: (package-install-file "ustar-withsub-0.1")
;; * installs but ignores subdirectory

M-: (package-install-file "ustar-withsub-0.1.tar")
;; * 28.2 - error
;; * with patch - installs and includes subdirectory

I believe sub directories should be allowed from this part of the docs
and the patch now allows for it as well as fixing the error.

    "...Files may also extract into subdirectories of the content
    directory. ..."
    
https://www.gnu.org/software/emacs/manual/html_node/elisp/Multi_002dfile-Packages.html

It would be to good to see if anyone can reproduce these as it looks
like more patches are needed to support sub directories?

1) for v7-withsub-0.1.tar so it looks at the top level for "-pkg.el"

2) include subdirectories when installing from a directory to match
functionality of installing from .tar.