Revise Connection.

Make _added_during_commit a regular instance variable.  Don't use
try/finally to reset it; just clear it at the start of a transaction.
XXX There was a test that needed to be removed, but it seemed to be
just a shallow test that try/finally was used.  Can't see any feature
that depends on specific of error handling: The txn is going to abort.

Remove unused _opened instance variable.
Split commit() into two smaller parts.
Get rid of extra manipulation of _creating.
Don't look for _p_serial of None; z64 is now required.
Undo local variable aliases in subtransaction methods.

Also, trivial change to pickle cache API -- get() works like dict get().

src/ZODB/tests/testCache.py

@@ -250,7 +250,7 @@ class CacheErrors(unittest.TestCase):
         self.cache = PickleCache(self.jar)
 
     def checkGetBogusKey(self):
-        self.assertRaises(KeyError, self.cache.get, p64(0))
+        self.assertEqual(self.cache.get(p64(0)), None)
         try:
             self.cache[12]
         except KeyError:

src/ZODB/tests/testConnection.py

@@ -124,16 +124,6 @@ class ConnectionDotAdd(unittest.TestCase):
                 "subobject was not stored")
         self.assert_(self.datamgr._added_during_commit is None)
 
-    def checkErrorDuringCommit(self):
-        # We need to check that _added_during_commit still gets set to None
-        # when there is an error during commit()/
-        obj = ErrorOnGetstateObject()
-        
-        self.datamgr.tpc_begin(self.transaction)
-        self.assertRaises(ErrorOnGetstateException,
-                self.datamgr.commit, obj, self.transaction)
-        self.assert_(self.datamgr._added_during_commit is None)
-
     def checkUnusedAddWorks(self):
         # When an object is added, but not committed, it shouldn't be stored,
         # but also it should be an error.

src/persistent/cPickleCache.c

@@ -90,7 +90,7 @@ process must skip such objects, rather than deactivating them.
 static char cPickleCache_doc_string[] =
 "Defines the PickleCache used by ZODB Connection objects.\n"
 "\n"
-"$Id: cPickleCache.c,v 1.91 2004/03/02 22:13:54 jeremy Exp $\n";
+"$Id: cPickleCache.c,v 1.92 2004/03/13 07:48:12 jeremy Exp $\n";
 
 #define DONT_USE_CPERSISTENCECAPI
 #include "cPersistence.h"
@@ -408,12 +408,10 @@ cc_get(ccobject *self, PyObject *args)
 
     r = PyDict_GetItem(self->data, key);
     if (!r) {
-	if (d) {
+	if (d)
 	    r = d;
-	} else {
-	    PyErr_SetObject(PyExc_KeyError, key);
-	    return NULL;
-	}
+	else
+	    r = Py_None;
     }
     Py_INCREF(r);
     return r;