Why does satellite-sync fail with "IOError: [Errno 22] Invalid argument" ?

Issue

• Satellite-sync fails with

Exception Handler Information
Traceback (most recent call last):
  File "/usr/bin/satellite-sync", line 143, in main
    return satsync.Runner().main()
  File "/usr/share/rhn/satellite_tools/satsync.py", line 225, in main
    ret = method()
  File "/usr/share/rhn/satellite_tools/satsync.py", line 342, in _step_packages
    self._affected_channels = self.syncer.import_packages()
  File "/usr/share/rhn/satellite_tools/satsync.py", line 1802, in import_packages
    return self._link_channel_packages()
  File "/usr/share/rhn/satellite_tools/satsync.py", line 1811, in _link_channel_packages
    package = short_package_collection.get_package(pid)
  File "/usr/share/rhn/satellite_tools/sync_handlers.py", line 240, in get_package
    return self._cache.cache_get(package_id)
  File "/usr/share/rhn/satellite_tools/syncCache.py", line 42, in cache_get
    compressed=self._compressed)
  File "/usr/share/rhn/common/rhnCache.py", line 78, in get
    return cache.get(name, modified)
  File "/usr/share/rhn/common/rhnCache.py", line 381, in get
    return self.cache.get(name, modified)
  File "/usr/share/rhn/common/rhnCache.py", line 351, in get
    pickled = self.cache.get(name, modified)
  File "/usr/share/rhn/common/rhnCache.py", line 242, in get
    fd = self.get_file(name, modified)
  File "/usr/share/rhn/common/rhnCache.py", line 279, in get_file
    fd = ReadLockedFile(name, modified)
  File "/usr/share/rhn/common/rhnCache.py", line 184, in __init__
    self.fd = self.get_fd(name, user, group, mode)
  File "/usr/share/rhn/common/rhnCache.py", line 207, in get_fd
    _lock(fd.fileno(), RDLOCK)
  File "/usr/share/rhn/common/rhnCache.py", line 58, in _lock
    fcntl.fcntl(fd, fcntl.F_SETLKW, lock)
IOError: [Errno 22] Invalid argument