I have problems using cmd as shell (should not do that, I know, but there is legacy code around).
It’s about quoting. If I define a line in .config as
ci\appveyor.bat this is presented to cmd.exe as
ci\\appveyor.bat. Likewise, a double quote
" is converted to
\". Needless to say, cmd.exe is not particularly happy about this.
I might of course, God forbid, have missed some documentation. But I basically see no way to create a command line to cmd.exe which does not mangle special characters.
The work around is to package all commands in a single script which is accessible without any
\ in the path. It works, but is somewhat clumsy.