'Determine the files to delete when rolling over.
More specific than the earlier method, which just used glob.glob().'

def getFilesToDelete(self):

    (dirName, baseName) = os.path.split(self.baseFilename)
    fileNames = os.listdir(dirName)
    result = []
    prefix = (baseName + '.')
    plen = len(prefix)
    for fileName in fileNames:
        if (fileName[:plen] == prefix):
            suffix = fileName[plen:]
            if self.extMatch.match(suffix):
                result.append(os.path.join(dirName, fileName))
    result.sort()
    if (len(result) < self.backupCount):
        result = []
    else:
        result = result[:(len(result) - self.backupCount)]
    return result
