Apply the differences between two sources to a working copy path.

        usage:
            1. merge sourceURL1[@N] sourceURL2[@M] [WCPATH]
            2. merge sourceWCPATH1@N sourceWCPATH2@M [WCPATH]
            3. merge -r N:M SOURCE[@REV] [WCPATH]
        
        1. In the first form, the source URLs are specified at revisions
           N and M.  These are the two sources to be compared.  The revisions
           default to HEAD if omitted.
        
        2. In the second form, the URLs corresponding to the source working
           copy paths define the sources to be compared.  The revisions must
           be specified.
        
        3. In the third form, SOURCE can be a URL, or working copy item
           in which case the corresponding URL is used.  This URL in
           revision REV is compared as it existed between revisions N and 
           M.  If REV is not specified, HEAD is assumed.
        
        WCPATH is the working copy path that will receive the changes.
        If WCPATH is omitted, a default value of '.' is assumed, unless
        the sources have identical basenames that match a file within '.':
        in which case, the differences will be applied to that file.

        ${cmd_option_list}

def do_merge(self, subcmd, opts, *args):
        """Apply the differences between two sources to a working copy path.

        usage:
            1. merge sourceURL1[@N] sourceURL2[@M] [WCPATH]
            2. merge sourceWCPATH1@N sourceWCPATH2@M [WCPATH]
            3. merge -r N:M SOURCE[@REV] [WCPATH]
        
        1. In the first form, the source URLs are specified at revisions
           N and M.  These are the two sources to be compared.  The revisions
           default to HEAD if omitted.
        
        2. In the second form, the URLs corresponding to the source working
           copy paths define the sources to be compared.  The revisions must
           be specified.
        
        3. In the third form, SOURCE can be a URL, or working copy item
           in which case the corresponding URL is used.  This URL in
           revision REV is compared as it existed between revisions N and 
           M.  If REV is not specified, HEAD is assumed.
        
        WCPATH is the working copy path that will receive the changes.
        If WCPATH is omitted, a default value of '.' is assumed, unless
        the sources have identical basenames that match a file within '.':
        in which case, the differences will be applied to that file.

        ${cmd_option_list}
        """
        print "'svn %s' opts: %s" % (subcmd, opts)
        print "'svn %s' args: %s" % (subcmd, args)