Running rebaseall on Cygwin

I tried building node.js on Cygwin and that caused errors, so someone in #node.js on freenode told me to run rebaseall on Cygwin to clean it up. So I tried that and I got the following message:

$ rebaseall
rebaseall: only ash or dash processes are allowed during rebasing
    Exit all Cygwin processes and stop all Cygwin services.
    Execute ash (or dash) from Start/Run... or a cmd or command window.
    Execute '/bin/rebaseall' from ash (or dash).

So I closed Cygwin, went to Start/Run and tried ash and dash but got the following alert:

Windows cannot find 'ash'. Make sure you typed the name correctly, and then try again. To search for a file, click the Start button, and then click Search.

So what am I supposed to do?

Try invoking ash by giving its full pathname. For example, if you installed Cygwin into C:\cygwin\, then you would type this into the Start/Run dialog box:

C:\cygwin\bin\ash.exe

This should start the ash shell, within which you can then invoke /bin/rebaseall.

If you are running Cygwin-X make sure the X is closed, not just the xterms.