[Bug 21047] New: cmd does not handle for %%a in ('command')

http://bugs.winehq.org/show_bug.cgi?id=21047

Summary: cmd does not handle for %%a in ('command')
           Product: Wine
           Version: 1.1.34
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: programs
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]

an example in bug 15359 shows that firefox's build script
relies on cmd being able to loop over the output of another
command using the for command:

FOR /F "tokens=2* delims=     " %%A IN ('REG QUERY "%MSVC6KEY%" /v
ProductDir') DO SET VC6DIR=%%B

Similar behavior is documented at
http://technet.microsoft.com/en-us/library/bb490909.aspx
but there it uses the /f option usebackq, and uses backquotes
rather than single quotes?