Check that f.keys() == [] right after creation -- this prevents bugs

like the one I just fixed to come back and haunt us.

Lib/test/test_bsddb.py

@@ -6,7 +6,7 @@
 import os
 import bsddb
 import tempfile
-from test_support import verbose
+from test_support import verbose, verify
 
 def test(openmethod, what):
 
@@ -15,6 +15,7 @@ def test(openmethod, what):
 
     fname = tempfile.mktemp()
     f = openmethod(fname, 'c')
+    verify(f.keys() == [])
     if verbose:
         print 'creation...'
     f['0'] = ''

Lib/test/test_dbm.py

@@ -4,11 +4,12 @@
 """
 import dbm
 from dbm import error
-from test_support import verbose
+from test_support import verbose, verify
 
 filename = '/tmp/delete_me'
 
 d = dbm.open(filename, 'c')
+verify(d.keys() == [])
 d['a'] = 'b'
 d['12345678910'] = '019237410982340912840198242'
 d.keys()

Lib/test/test_gdbm.py

@@ -5,11 +5,12 @@
 
 import gdbm
 from gdbm import error
-from test_support import verbose, TestFailed
+from test_support import verbose, verify, TestFailed
 
 filename= '/tmp/delete_me'
 
 g = gdbm.open(filename, 'c')
+verify(g.keys() == [])
 g['a'] = 'b'
 g['12345678910'] = '019237410982340912840198242'
 a = g.keys()