def parse(self, m, prefix=None):
        """Parse messages sent by the 'buildbot-cvs-mail' program.
        """
        # The mail is sent from the person doing the checkin. Assume that the
        # local username is enough to identify them (this assumes a one-server
        # cvs-over-rsh environment rather than the server-dirs-shared-over-NFS
        # model)
        name, addr = parseaddr(m["from"])
        if not addr:
            # no From means this message isn't from buildbot-cvs-mail
            return None
        at = addr.find("@")
        if at == -1:
            author = addr  # might still be useful
        else:
            author = addr[:at]
        author = util.bytes2unicode(author, encoding="ascii")

        # CVS accepts RFC822 dates. buildbot-cvs-mail adds the date as
        # part of the mail header, so use that.
        # This assumes cvs is being access via ssh or pserver, so the time
        # will be the CVS server's time.

        # calculate a "revision" based on that timestamp, or the current time
        # if we're unable to parse the date.
        log.msg('Processing CVS mail')
        dateTuple = parsedate_tz(m["date"])
        if dateTuple is None:
            when = util.now()
        else:
            when = mktime_tz(dateTuple)

        theTime = datetime.datetime.utcfromtimestamp(float(when))
        rev = theTime.strftime('%Y-%m-%d %H:%M:%S')

        catRE = re.compile(r'^Category:\s*(\S.*)')
        cvsRE = re.compile(r'^CVSROOT:\s*(\S.*)')
        cvsmodeRE = re.compile(r'^Cvsmode:\s*(\S.*)')
        filesRE = re.compile(r'^Files:\s*(\S.*)')
        modRE = re.compile(r'^Module:\s*(\S.*)')
        pathRE = re.compile(r'^Path:\s*(\S.*)')
        projRE = re.compile(r'^Project:\s*(\S.*)')
        singleFileRE = re.compile(r'(.*) (NONE|\d(\.|\d)+) (NONE|\d(\.|\d)+)')
        tagRE = re.compile(r'^\s+Tag:\s*(\S.*)')
        updateRE = re.compile(r'^Update of:\s*(\S.*)')
        comments = ""
        branch = None
        cvsroot = None
        fileList = None
        files = []
        isdir = 0
        path = None
        project = None

        lines = list(body_line_iterator(m))
        while lines:
            line = lines.pop(0)
            m = catRE.match(line)
            if m:
                category = m.group(1)
                continue
            m = cvsRE.match(line)
            if m:
                cvsroot = m.group(1)
                continue
            m = cvsmodeRE.match(line)
            if m:
                cvsmode = m.group(1)
                continue
            m = filesRE.match(line)
            if m:
                fileList = m.group(1)
                continue
            m = modRE.match(line)
            if m:
                # We don't actually use this
                # module = m.group(1)
                continue
            m = pathRE.match(line)
            if m:
                path = m.group(1)
                continue
            m = projRE.match(line)
            if m:
                project = m.group(1)
                continue
            m = tagRE.match(line)
            if m:
                branch = m.group(1)
                continue
            m = updateRE.match(line)
            if m:
                # We don't actually use this
                # updateof = m.group(1)
                continue
            if line == "Log Message:\n":
                break

        # CVS 1.11 lists files as:
        #   repo/path file,old-version,new-version file2,old-version,new-version
        # Version 1.12 lists files as:
        #   file1 old-version new-version file2 old-version new-version
        #
        # files consists of tuples of 'file-name old-version new-version'
        # The versions are either dotted-decimal version numbers, ie 1.1
        # or NONE. New files are of the form 'NONE NUMBER', while removed
        # files are 'NUMBER NONE'. 'NONE' is a literal string
        # Parsing this instead of files list in 'Added File:' etc
        # makes it possible to handle files with embedded spaces, though
        # it could fail if the filename was 'bad 1.1 1.2'
        # For cvs version 1.11, we expect
        #  my_module new_file.c,NONE,1.1
        #  my_module removed.txt,1.2,NONE
        #  my_module modified_file.c,1.1,1.2
        # While cvs version 1.12 gives us
        #  new_file.c NONE 1.1
        #  removed.txt 1.2 NONE
        #  modified_file.c 1.1,1.2

        if fileList is None:
            log.msg('CVSMaildirSource Mail with no files. Ignoring')
            return None       # We don't have any files. Email not from CVS

        if cvsmode == '1.11':
            # Please, no repo paths with spaces!
            m = re.search('([^ ]*) ', fileList)
            if m:
                path = m.group(1)
            else:
                log.msg(
                    'CVSMaildirSource can\'t get path from file list. Ignoring mail')
                return
            fileList = fileList[len(path):].strip()
            singleFileRE = re.compile(
                r'(.+?),(NONE|(?:\d+\.(?:\d+\.\d+\.)*\d+)),(NONE|(?:\d+\.(?:\d+\.\d+\.)*\d+))(?: |$)')
        elif cvsmode == '1.12':
            singleFileRE = re.compile(
                r'(.+?) (NONE|(?:\d+\.(?:\d+\.\d+\.)*\d+)) (NONE|(?:\d+\.(?:\d+\.\d+\.)*\d+))(?: |$)')
            if path is None:
                raise ValueError(
                    'CVSMaildirSource cvs 1.12 require path. Check cvs loginfo config')
        else:
            raise ValueError(
                'Expected cvsmode 1.11 or 1.12. got: %s' % cvsmode)

        log.msg("CVSMaildirSource processing filelist: %s" % fileList)
        while(fileList):
            m = singleFileRE.match(fileList)
            if m:
                curFile = path + '/' + m.group(1)
                files.append(curFile)
                fileList = fileList[m.end():]
            else:
                log.msg('CVSMaildirSource no files matched regex. Ignoring')
                return None   # bail - we couldn't parse the files that changed
        # Now get comments
        while lines:
            line = lines.pop(0)
            comments += line

        comments = comments.rstrip() + "\n"
        if comments == '\n':
            comments = None
        return ('cvs', dict(author=author, files=files, comments=comments,
                            isdir=isdir, when=when, branch=branch,
                            revision=rev, category=category,
                            repository=cvsroot, project=project,
                            properties=self.properties))