Fixes bug #1117761

bsddb.*open() methods cachesize parameter wouldn't work (raised an
internal bsddb.db exception when it was given).  The set_cachesize
call needed to be moved from the DB object to the DBEnv since the env
was introduced to allow for threading.

(will backport to 2.4)
diff --git a/Lib/bsddb/__init__.py b/Lib/bsddb/__init__.py
index 68f1032..c004c08 100644
--- a/Lib/bsddb/__init__.py
+++ b/Lib/bsddb/__init__.py
@@ -287,10 +287,9 @@
             cachesize=None, lorder=None, hflags=0):
 
     flags = _checkflag(flag, file)
-    e = _openDBEnv()
+    e = _openDBEnv(cachesize)
     d = db.DB(e)
     d.set_flags(hflags)
-    if cachesize is not None: d.set_cachesize(0, cachesize)
     if pgsize is not None:    d.set_pagesize(pgsize)
     if lorder is not None:    d.set_lorder(lorder)
     if ffactor is not None:   d.set_h_ffactor(ffactor)
@@ -305,9 +304,8 @@
             pgsize=None, lorder=None):
 
     flags = _checkflag(flag, file)
-    e = _openDBEnv()
+    e = _openDBEnv(cachesize)
     d = db.DB(e)
-    if cachesize is not None: d.set_cachesize(0, cachesize)
     if pgsize is not None: d.set_pagesize(pgsize)
     if lorder is not None: d.set_lorder(lorder)
     d.set_flags(btflags)
@@ -324,9 +322,8 @@
             rlen=None, delim=None, source=None, pad=None):
 
     flags = _checkflag(flag, file)
-    e = _openDBEnv()
+    e = _openDBEnv(cachesize)
     d = db.DB(e)
-    if cachesize is not None: d.set_cachesize(0, cachesize)
     if pgsize is not None: d.set_pagesize(pgsize)
     if lorder is not None: d.set_lorder(lorder)
     d.set_flags(rnflags)
@@ -339,8 +336,13 @@
 
 #----------------------------------------------------------------------
 
-def _openDBEnv():
+def _openDBEnv(cachesize):
     e = db.DBEnv()
+    if cachesize is not None:
+        if cachesize >= 20480:
+            e.set_cachesize(0, cachesize)
+        else:
+            raise error, "cachesize must be >= 20480"
     e.open('.', db.DB_PRIVATE | db.DB_CREATE | db.DB_THREAD | db.DB_INIT_LOCK | db.DB_INIT_MPOOL)
     return e
 
diff --git a/Lib/test/test_bsddb.py b/Lib/test/test_bsddb.py
index 7a0c97c..513e541 100755
--- a/Lib/test/test_bsddb.py
+++ b/Lib/test/test_bsddb.py
@@ -14,7 +14,7 @@
     openflag = 'c'
 
     def setUp(self):
-        self.f = self.openmethod[0](self.fname, self.openflag)
+        self.f = self.openmethod[0](self.fname, self.openflag, cachesize=32768)
         self.d = dict(q='Guido', w='van', e='Rossum', r='invented', t='Python', y='')
         for k, v in self.d.iteritems():
             self.f[k] = v