avoid spurious errors on exit, especially for scripts, such as zeopack.

effective. :)

references across databases when the referenced database has an empty
name.

was astronomical.  Also greatly simplified the code.

refactoring to simplify the data structures to fix a serious memory
bug: the cache uses waaaay the heck too much.

object will properly switch to longs when over/underflowing 32-bit values

- Cache records are written in several stems.  If a process exits
    after writing begins and before it is finishes, the cache will be
    corrupt on restart.  The way records are writted was changed to
    make cache record updates atomic.

- There was no lock file to prevent opening a cache multiple times
    at once, which would lead to corruption.  Persistent caches now
    use lock files, in the same way that file storages do.

- A bug in the cache-opening logic led to cache failure in the
    unlikely event that a cache has no free blocks.

When using ZEO Client Storages, Errors occured when trying to store
objects too big to fit in the ZEO cache file.

(backport from trunk)

(backport from trunk)

This module needs to move to the Zope 2 tree.

versions of objects.

uncommitted data is placed.

  only affects zpkg.

distutils-compatible method but it failed miserably.

(hang). This was accomonied by a critical log message along the
lines of: "RuntimeError: dictionary changed size during iteration".