execute shell scripts by call-process in msys2 environment

[holgar . sperr]

Hi,

I wanted to activate version control from within Emacs (26.1 under msys2) using 
the rcs backend provided through msys2 repository.

The problem is now that for instance the registering by 'ci' is not successful, 
because the corresponding shell script is not found.

What I do understand by now: Processes in this setup are initialized by 
'cmd.exe'.

Is there an easy solution to circumvent this problem?

Or would you recommend a different setup, e.g. ezwinports? What should be 
considered in this case?

(I do like msys2 for scripting and easy administration and would therefore 
prefer a msys2 solution.)

Thanks for any help,
Holger