Happy with remote-shell $0, and its PATH

[積丹尼 Dan Jacobson]

(info "(tramp) Android shell setup") says

   • ‘sh’ must be specified for remote shell since Android devices do
     not provide ‘/bin/sh’.  ‘sh’ will then invoke whatever shell is
     installed on the device with this setting:

          (add-to-list 'tramp-connection-properties
                     (list (regexp-quote "192.168.0.26") "remote-shell" "sh"))

I have an idea,
because we are already talking to the shell,
can't we just tell it somehow to use "$0"?!

Then we don't have to worry about PATHs, nor if there is only "bash" or
"sh" there.

That way instead of sending
# exec env TERM='dumb' ... PS2='' PS3='' sh
it could send
# exec env TERM='dumb' ... PS2='' PS3='' $0
and (perhaps) always work!

In fact, as we are already in a shell, have tramp just send
#          TERM='dumb' ... PS2='' PS3=''
Brilliant, no?

Furthermore, at

   • TRAMP requires preserving ‘PATH’ environment variable from user
     settings.  Android devices prefer ‘/system/xbin’ path over
     ‘/system/bin’.  Both of these are set as follows:

          (add-to-list 'tramp-remote-path 'tramp-own-remote-path)
          (add-to-list 'tramp-remote-path "/system/xbin")

what if we are happy with the path the remote ssh provides us,
and don't want to change it? I.e., tramp should just use the ls, cp, rm,
etc. that it finds on the path already in the ssh shell... so do mention
how to enforce that.