code that shows bug in python file locking code

import os
import fcntl
from multiprocessing import Process

class SingleInstanceError: pass
class InterProcessLockFcntl:
    type = "fcntl"
    def __init__(self, name=None, raise_on_no_lock=False, Tag=""):
        self.lockf = 0
        self.raise_on_no_lock = raise_on_no_lock
        self.Tag = Tag
        if not name:
            name = sys.argv[0]
        self.name = name                # base64.b64encode(name).replace('=','')
        self.fname = os.path.join('/tmp',self.name + '.lock')
        assert(os.path.isdir('/tmp'))

    def acquire(self):
        self.lockf = open(self.fname, 'w')
        try:
            fcntl.flock(self.lockf, fcntl.LOCK_EX | fcntl.LOCK_NB)
        except IOError:
            self.lockf.close()
            self.lockf = 0
            if self.raise_on_no_lock is True:
                raise SingleInstanceError
            else:
                print self.Tag, "NO ACQUIRE"
                return False
        print self.Tag, "ACQUIRE"
        return True

    def release(self):
        try:
            print self.Tag, "RELEASE"
            os.unlink(self.fname)
            self.lockf.close()
        except OSError:
            print self.Tag, "RELEASE - FAIL"

def f(name, i):
    l = InterProcessLockFcntl( name, Tag=i )
    rc = l.acquire()
    if rc is True:
        l.release()

for num in range(100):
    Process(target=f, args=("yh_lock_file", num)).start()

sys.exit(1)