shrink local fsdb by removing dangling and/or corrupted files

           return number of deleted files

def shrink_local_fsdb(self, dangling=True, corrupted=True, dryrun=False):
        '''shrink local fsdb by removing dangling and/or corrupted files

           return number of deleted files
        '''
        log.debug('shrinking local fsdb [danglings={}, corrupted={}]'.format(dangling, corrupted))
        count = 0
        if dangling:
            for fid in self.dangling_files():
                log.info("shrinking: removing dangling  '{}'".format(fid))
                if not dryrun:
                    self._fsdb.remove(fid)
                count += 1
        if corrupted:
            for fid in self._fsdb.corrupted():
                log.info("shrinking: removing corrupted '{}'".format(fid))
                if not dryrun:
                    self._fsdb.remove(fid)
                count += 1
        return count