tramp and shell, problem on windows 7

[Shuguang Sun]

Hi all,

Windows7,
GNU Emacs 27.0.50 (build 1, x86_64-w64-mingw32) of 2017-10-21

- Problem 1: tramp and dired-do-shell-command:  start: Unknown job: /b
Why "start /b" is called remote side?

When I run tramp (plink) and go to a remote buffer (dired mode), run
dired-do-shell-command (!) on marked file (for example, R CMD BATCH * &).
It popup the buffer of * Async Shell Command *, and the command is not run
but a message "start: Unknown job: /b" which looks it runs the windows-like
command "start /b ..." on the remote shell.

- Problem 2: tramp and shell: env: c:/bin/ : No such file or directory
where "c:/" comes?

In a tramp dried buffer, call shell which suppose to raise the shell buffer
on remote server. However, I got error messge in the * shell * buffer that
"env: c:/bin/ : No such file or directory". I don't know where the "c:/"
comes from. When shell is called, it reads the remote path in the minibufer
with promotes 
"/plink:user@host:/path/to/dired/C:/Users/username/emacs/libexec/emacs/27.0.50/x86_64-w64-mingw32/cmdproxy.exe",
and I change it to "/plink:user@host:/bin/", and then I got error message
above. Below is the tracking:

Searching for
‘C:/Users/username/emacs/libexec/emacs/27.0.50/x86_64-w64-mingw32/cmdproxy.exe’....
Tramp: Opening connection for user@host using plink...
Tramp: Sending command ‘plink -l user  -ssh host && exit || exit’
Tramp: Waiting for prompts from remote shell...
Tramp: Sending password
Tramp: Waiting for prompts from remote shell...done
Tramp: Found remote shell prompt on ‘host’
Tramp: Opening connection for user@host using plink...done


Best Regards,
Shuguang Sun